Paradise Lost

Consisting of thirty-two atolls and one raised coral island dispersed over an area of the central Pacific larger than India, Kiribati (pronounced KIRR-ih-bass) is a breathtaking tropical paradise.Footnote ¹ Straddling the equator, its atolls are surrounded and laced through with shimmering turquoise waters. Towering coconut palm trees and stilt houses line its beaches. Marine life is abundant; fishers in sarongs gather shellfish at low tide. But for Kiribati’s roughly 119,000 permanent residents, the beauty and wonder of their ancestral homeland is overshadowed by impending cataclysm: the devastating impacts of global climate change.

Historically, Kiribati has not suffered from cyclones and similar severe weather, since those rarely occur near the equator.Footnote ² However, climate scientists have long warned of changing weather patterns in the Pacific, predicting that global warming would cause island nations to experience severe weather events with greater frequency.Footnote ³ In 2015, heavy seas and winds from Tropical Cyclone Pam struck Kiribati, flooding and destroying homes and buildings, contaminating freshwater wells, and destroying sea walls.Footnote ⁴ Already reliant on significant development assistance, with the lowest gross domestic product of any sovereign state in Oceania, Kiribati lacks the resources needed to recover from a natural disaster of this magnitude.Footnote ⁵

More terrifying yet for Kiribati is the rising sea. Kiribati is a low-lying nation, with most land less than two meters above sea level.Footnote ⁶ According to the Intergovernmental Panel on Climate Change (IPCC), between 1901 and 1971 the average rate of sea level rise was 1.3mm per year, increasing to 1.9mm per year between 1971 and 2006, and further accelerating to 3.7mm per year between 2006 and 2018.Footnote ⁷ By 2100, the sea level around Kiribati is estimated to rise between 520 mm (20.5 inches) and 910 mm (36 inches), and possibly much more.Footnote ⁸ In 1999, two of Kiribati’s islands, Abanuea and Tebua Tarawa, flooded and disappeared underwater entirely.Footnote ⁹ As these trends continue, much more of Kiribati’s landmass will be lost to the rising sea.Footnote ¹⁰ Nonetheless, the most probable and imminent existential crisis Kiribati faces is the threat of higher seas and more frequent extreme weather combining to render its islands uninhabitable long before they are buried by the sea.Footnote ¹¹

The principal cause of rising sea levels is global warming.Footnote ¹² The IPCC reports global surface temperature reaching 1.1°C above 1850–1900 levels in 2011–2020.Footnote ¹³ Rising global temperature is melting glaciers and ice sheets at an unprecedented pace, all the while expanding the volume of the ocean as sea water warms. The IPCC’s leading headline in its 2023 Synthesis Report is that “[h]uman activities, principally through emissions of greenhouse gases, have unequivocally caused global warming.”Footnote ¹⁴ Greenhouse gases (GHGs) – carbon dioxide, methane, nitrous oxide, and fluorinated gases – trap heat energy from the sun within the earth’s atmosphere, raising global surface temperatures.Footnote ¹⁵ GHGs are created by a host of industrial, agricultural, and consumer practices, including the harvesting, transporting, and burning of coal, oil, natural gas, solid waste, and trees. Past and present GHG emissions have already locked in considerable environmental damage. The IPCC concludes that “[s]ea level rise is unavoidable for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and sea levels will remain elevated for thousands of years.”Footnote ¹⁶ However, the IPCC also affirms that “deep, rapid, and sustained GHG emissions reductions would limit further sea level rise acceleration and projected long-term sea level rise commitment.”Footnote ¹⁷

Put concretely, whether Kiribati faces half a meter, a full meter, or more than a meter of sea level rise by 2100 depends on the extent to which the international community is prepared to mitigate global warming by making “deep, rapid, and sustained” reductions to global GHG emissions. Even under optimistic forecasts, however, Kiribati will need robust sea walls and elevated dwellings to remain habitable. If Kiribati’s citizens are to remain on their islands, the international community must assist Kiribati in implementing adaptation measures to cope with higher sea levels. Mitigation and adaptation are essentially the two policy choices available to address climate change constructively.

Kiribati is sometimes referred to as the “canary in the coal mine” of climate change, since it was among the first countries to suffer devastating harm from global warming, serving as a warning to others.Footnote ¹⁸ Many other countries are now experiencing similar effects, however, and there is mounting evidence that global warming is accelerating faster than expected just a few years ago. Three years after authoring a widely publicized “warning of a climate emergency” that attracted 15,000 expert signatories,Footnote ¹⁹ seasoned climate scientists William Ripple and Christopher Wolf offered this alarming assessment:

These accelerating changes to the global environment pose grave dangers not only for low-lying island nations, such as Kiribati, but also for countries elsewhere, whether they be in the Global North or the Global South. Climate change knows no borders, and its adverse effects threaten to leave no people or territory unharmed.

This chapter examines the international community’s efforts to address climate change. As we shall see, the overarching method is international cooperation within an institutional framework supplied by international law. States and international organizations have established a supranational framework – the UN Framework Convention on Climate Change (UNFCCC) and related instruments – to articulate and implement mitigation and adaptation policies. We argue that this framework reflects the norms of mandatory cooperation, and it holds cautious promise for equitably allocating the costs of mitigation and adaptation in developing countries hard hit by climate change, such as Kiribati.

Governing the Climate Commons

When the UNFCCC entered into force in 1994, the international community formally recognized that “change in the Earth’s climate and its adverse effects are a common concern of humankind” and that this common concern requires “the widest possible cooperation by all countries and their participation in an effective and appropriate international response.”Footnote ²¹ Similarly, the Convention on Biodiversity identifies the “conservation of biological diversity” (not animal life per se) as “a common concern of humankind.”Footnote ²² By explicitly specifying in treaties that these issues constitute common concerns of humanity, the international community has signaled that states’ sovereign rights to exploit resources within their domestic jurisdiction are coupled with a concomitant obligation to cooperate with other states in advancing sustainable development and preventing catastrophic environmental harm.

In 2015, representatives from 196 states met near Paris to negotiate and draft an agreement that would address climate change at the global level. These talks ultimately produced the Paris Agreement.Footnote ²³ Its principal aim is to promote the adoption of policies that will reduce GHG emissions, thereby “[h]olding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.”Footnote ²⁴ The scientific consensus is that warming above 2°C will result in “irreversible, catastrophic harm.”Footnote ²⁵

A further objective of the Paris Agreement is “[i]ncreasing the ability to adapt to the adverse impacts of climate change and foster climate resilience and low greenhouse gas emissions development.”Footnote ²⁶ The Global Commission on Adaptation points to several serious harms likely to occur if the international community does not provide adequate resources for adaptation:

• Without adaptation, climate change may depress growth in global agriculture yields up to 30 percent by 2050. The 500 million small farms around the world will be most affected.

• The number of people who lack sufficient water at least one month per year will soar from 3.6 billion today to more than 5 billion by 2050.

• Rising seas and greater storm surges could force hundreds of millions of people in coastal cities from their homes, with a total cost to coastal urban areas of more than USD 1 trillion each year by 2050.

• Climate change could push more than 100 million people in developing countries below the poverty line by 2030.Footnote ²⁷

As the chief means of attaining mitigation and adaptation goals, the Paris Agreement envisions all countries developing and periodically ratcheting up “nationally determined contributions” (NDCs) to address climate change.Footnote ²⁸ NDCs are to be submitted to the United Nations every five years and then used to assess states-parties’ compliance with their ongoing commitments, as we explain in this section.Footnote ²⁹ Sensitive to the concerns of developing countries, the preamble affirms “the principle of equity and common but differentiated responsibilities and respective capabilities.”Footnote ³⁰ More concretely, the Paris Agreement provides a framework for preexisting commitments of USD 100 billion a year in climate finance for developing countries by 2020, and for further financial assistance subsequently.Footnote ³¹ Although the plan’s success depends on the willingness of countries to follow through on these commitments and develop and adhere to meaningful NDCs, we have suggested in previous writing that the obligation of states to do so is explained by the idea that states, severally and jointly, are fiduciaries of humanity.Footnote ³²

Implementation of the Paris Agreement is followed and pursued by the institutional framework inaugurated by the UNFCCC. The centerpiece of this framework is the annual Conference of the Parties to the UNFCCC (COP). The COP is the supreme decision-making body of the UNFCCC. Running concurrently is the Conference of the Parties, serving as the Meeting of the Parties of the Paris Agreement (the CMA series), and the Conference of the Parties to the Kyoto Protocol (the CMP series). So, for example, in Glasgow in 2021 there were concurrent meetings of the 26th session of the Conference of the Parties to the UNFCCC (COP26), the 16th session of the Conference of the Parties serving as the Meeting of the Parties to the Kyoto Protocol (CMP16), and the 3rd session of the Conference of the Parties serving as the Meeting of the Parties to the Paris Agreement (CMA3). The main result of COP26/CMA3 was the Glasgow Climate Pact, an agreement of the 197 Parties in attendance that built on various commitments found in the Paris Agreement.Footnote ³³ Before turning to some of the specific measures in the Glasgow Pact, however, we set out now the numerous ways the legal regime established by the Paris Agreement reflects the norms of mandatory cooperation.

Like the UNFCCC, the Paris Agreement acknowledges that mitigating climate change and its adverse effects is “a common concern of humankind.”Footnote ³⁴ Although the Paris Agreement is careful to protect developing countries with the principle of “common but differentiated responsibilities,” all states parties are expected to participate in the Agreement’s regime of international cooperation. Nonetheless, while the Kyoto Protocol establishes legally binding GHG emission-reduction targets for developed countries,Footnote ³⁵ the Paris Agreement does not. The Kyoto Protocol adopts a “top-down” approach that imposes emission-reduction targets on wealthier nations. The Paris Agreement, by contrast, relies on a “bottom-up” method that requires all states to develop NDCs, either by themselves or jointly with others, including through the use of “internationally transferred mitigation outcomes” (typically, a developed country would finance realization of a developing country’s NDC).Footnote ³⁶ The Agreement calls for each party’s successive NDC to ratchet up or “represent a progression beyond” the prior NDC.Footnote ³⁷ States parties are likewise legally required to submit their NDCs to the United Nations and a public registry, report on progress every two years, and have their progress reports reviewed by technical experts and peers.Footnote ³⁸ In fact, each state’s NDCs and progress toward them are transparently displayed and assessed on a publicly available website.Footnote ³⁹ The Agreement further envisions a “global stocktake” every five years to assess collective progress toward its objectives.Footnote ⁴⁰

The Paris Agreement seeks to strike a balance that takes into account state autonomy and self-determination, on the one hand, and the urgent need for a global response to climate change, on the other. State autonomy is respected through the use of NDCs that states are legally entitled to design and implement as they wish. The demands of climate change are reflected in the legal requirement to establish, implement, and report periodically on progress toward NDCs. This activity is wedded to the annual COP meetings under the UNFCCC framework, as described above. In this context, states retain an overarching obligation from the UNFCCC to “protect the climate system for the benefit of present and future generations of humankind,”Footnote ⁴¹ and to do so cooperatively, such as through the negotiated use of “internationally transferred mitigation outcomes.”Footnote ⁴² Thus, explicitly and implicitly, the UNFCCC and the Paris Agreement require states to negotiate with one another in good faith, and on an ongoing basis, for the purpose of developing and implementing NDCs capable of achieving collectively the goals of the Paris Agreement. In the event of a dispute concerning the interpretation or application of the UNFCCC or the Paris Agreement, the controversy is remitted to the International Court of Justice (ICJ), arbitration, or conciliation.Footnote ⁴³ The Paris Agreement thus embraces a form of mandatory cooperation akin to the form established under the UN Convention on the Law of the Sea,Footnote ⁴⁴ where contending parties are obligated to negotiate in good faith, resorting to third-party dispute resolution only if necessary.

The principle of sovereign equality is respected under the Paris Agreement because no state is entitled to dictate terms to another, and every state is ultimately responsible for the content of its NDC. The principle of joint stewardship is put into action by the Paris Agreement’s delegation to states of the responsibility to craft meaningful NDCs to reduce GHG emissions and address the adverse effects of climate change. Joint stewardship assumes an institutional and democratic form through the Paris Agreement’s annual COP and CMA conference series. Every party has one vote, allowing the COP/CMA conferences to speak collectively on behalf of all.Footnote ⁴⁵

The Glasgow Climate Pact

Six years after the signing of the Paris Agreement, COP26 in Glasgow gave the international community an opportunity to assess progress, grapple with challenges, and strengthen NDCs. Held during the COVID-19 pandemic, COP26 demonstrated states’ willingness to take new decisions and strengthen commitments. Over fifty formal decisions were adopted.Footnote ⁴⁶ In addition, COP26 secured near-global net zero NDCs from 153 countries, such that over 90 percent of world gross domestic product and around 90 percent of global emissions are now covered by net zero commitments.Footnote ⁴⁷ Significantly, the Glasgow Pact cemented 1.5°C as the primary global temperature ceiling, with the more severe impacts of 2°C warming emphasized.Footnote ⁴⁸ The Pact also emphasized near-term action aimed at 2030, such as “reducing global carbon dioxide emissions by 45 per cent by 2030 relative to the 2010 level and to net zero around mid-century as well as deep reductions in other greenhouse gases.”Footnote ⁴⁹ The Paris Agreement, by contrast, only refers to achieving net-zero “in the second half of this century.”Footnote ⁵⁰ The Glasgow Pact also invited the Parties to “consider further actions to reduce by 2030” methane and other non-carbon dioxide GHGs, whereas the Paris Agreement is silent on methane and other non-carbon dioxide GHGs.Footnote ⁵¹ Possibly the most significant novelty in the Pact, however, is its call on the Parties to accelerate “efforts towards the phasedown of unabated coal power and phase-out of inefficient fossil fuel subsidies.”Footnote ⁵² This is the first time an international instrument has expressly called for a reduction in the use of coal, which alone is responsible for roughly 40 percent of all current carbon dioxide emissions.Footnote ⁵³

The many joint commitments in the Glasgow Pact are the product of negotiation and cooperation that aims for consensus within the COP/CMA framework. Crucially, these multilateral decisions and commitments include major GHG producers, such as China, India, Russia, and the United States. In the case of the provision on coal, China and India resisted the original language that called for a phasing out of coal power but did agree to a progressive “phasedown.”Footnote ⁵⁴ This is consistent with mandatory cooperation’s norm calling on states to negotiate matters of common concern in good faith without prescribing predetermined outcomes.

Mandatory cooperation in this context assumes that states wear two hats. One is the hat of their people’s representative, a role that requires them to bargain zealously for their people’s welfare. The other hat is worn as a joint steward of humanity, where they are called on, with other states, to safeguard the earth’s environment. As their people’s representative, they are entitled to seek reasonable accommodations consistent with “the principle of equity and common but differentiated responsibilities.”Footnote ⁵⁵ As a steward of humanity, they are tasked with ensuring that equity and reasonableness frame the claims made by individual states, including their own. Plausibly, China and India’s insistence on “phasedown” rather than “phase out” falls within the margin of maneuver they enjoy as both their people’s representatives and good stewards of humanity.

Some might be surprised that China and India compromised at all. Why did they not just walk away and refuse to set up any standard for measuring the reduction of coal power? Let us assume that China and India believed that it was in their interest to compromise, either for the sake of reputational gain or because they themselves were being affected by climate change or were otherwise concerned about its possible effects on them. Whatever their actual motivation, the presence of a self-interested reason for compromising does not imply that they did not have an obligation to negotiate in good faith. By agreeing to take part in the COP/CMA process, they agreed to negotiate and participate in good faith, and thereby incurred an obligation to do so. Moreover, they would likely present themselves and their interlocutors as having an obligation to negotiate in good faith, since good faith is the least that can be reasonably expected of contending parties who must negotiate a collective approach to a common concern. Accordingly, for Parties within the COP/CMA framework, good faith and mandatory cooperation are the overarching practices to which they are committed.

It is equally clear from the record of proceedings and negotiations that the Parties view the provisions of the Glasgow Pact as binding and authoritative. The Parties’ self-understanding of the Pact is noteworthy because, unlike the Paris Agreement, which is formally a treaty within the UN system, the Glasgow Pact is not a treaty but rather a “soft law” instrument of international law. As a decision of COP26/CMA3 (Decision 1/CMA.3), it resembles in form a resolution of the UN General Assembly. Now, many of the Pact’s provisions recall and seek urgent implementation of articles from the Paris Agreement. For example, paragraph 26 “[e]mphasizes the urgent need for Parties to increase their efforts to collectively reduce emissions through accelerated action and implementation of domestic mitigation measures in accordance with … the Paris Agreement.”Footnote ⁵⁶ In these cases, the Pact can piggyback on the Agreement by serving as an authoritative interpretation of the relevant articles of the Agreement, which unquestionably are legally binding under international law.

The open-textured nature of many of the Agreement’s provisions means that even the novel and specific commitments from the Pact, such as the coal phasedown, may be read as giving content to those provisions. For example, the coal phasedown may be understood as part of the commitment from Article 4(1) of the Agreement to “reach global peaking of greenhouse gas emissions as soon as possible.”Footnote ⁵⁷ Moreover, even where the Glasgow Pact enshrines commitments that cannot be brought into the four corners of the Paris Agreement, Joanna Depledge, Miguel Saldivia, and Cristine Peñasco rightly observe that “COP decisions still shape the obligations and expectations of parties and stakeholders, and have the advantage of immediate and global applicability, since they do not require domestic ratification to take effect.”Footnote ⁵⁸

Regrettably, not everything on which states agreed prior to Glasgow has come to pass, exposing the relative frailty of UNFCCC framework. The Glasgow Pact notes “with deep regret” the failure of developed countries to meet the goal previously set of mobilizing jointly USD 100 billion per year by 2020 to support mitigation in developing countries, while welcoming increased transparency and pledges that surpass this goal.Footnote ⁵⁹ The Pact also calls on developed countries “to at least double their collective provision of climate finance for adaptation of developing parties from 2019 levels by 2025.”Footnote ⁶⁰ It is far from clear that even this apparently ambitious goal is adequate. The International Energy Agency estimates that “[b]y the end of the 2020s, annual capital spending on clean energy in [developing] economies needs to expand by more than seven times, to above USD 1 trillion, in order to put the world on track to reach net-zero emissions by 2050.”Footnote ⁶¹ While price-tags such as this are eye-watering, the Global Commission on Adaptation has calculated that investing USD 1.8 trillion globally in five adaptation areas – early warning systems, infrastructure resiliency, dryland crop production, protecting mangroves, and water resource management resiliency – would produce total net benefits of USD 7.1 trillion.Footnote ⁶² The challenge for policymakers will be harnessing the ambition underlying the Glasgow Pact to convince developed countries to invest jointly in mitigation and adaptation measures that are in their long-term economic as well as climate interest.

COP28 and the First Global Stocktake

Held in Dubai in December 2023, COP28 brought together more than 150 heads of state and government and some 85,000 participants, including representatives of national delegations, civil society organizations, business, indigenous peoples, and international organizations. The major outcome from the conference was the first global stocktake on climate matters prescribed by the Paris Agreement.Footnote ⁶³ In what the United Nations hailed as “a demonstration of global solidarity,” nearly two hundred parties reached consensus on the stocktake, which provides assessments of mitigation and adaptation efforts to date, the state of the climate, and prescriptions on what needs to done.Footnote ⁶⁴ The headline-grabbing novelty was the stocktake’s call for “[p]hasing out inefficient fossil fuel subsidies” and “[t]ransitioning away from fossil fuels.”Footnote ⁶⁵ Expressing “serious concern that 2023 is set to be the warmest year on record,” the agreement calls on parties to implement “deep, rapid and sustained reductions in global greenhouse gas emissions of 43 per cent by 2030 and 60 per cent by 2035” so as to limit warming to 1.5°C with limited overshoot.Footnote ⁶⁶ Reaffirming “equity and the principle of common but differentiated responsibilities,” the stocktake recognizes that time frames for peaking temperatures in different countries “may be shaped by sustainable development, poverty eradication needs and equity and be in line with different national circumstances.”Footnote ⁶⁷ Mitigation prescriptions include “[t]ripling renewable energy capacity globally and doubling the global average annual rate of energy efficiency improvements by 2030.”Footnote ⁶⁸ The stocktake likewise affirms ambitious adaptation measures to contend with the effects of climate change, especially on the most vulnerable states, such as Kiribati. For example, the Parties acknowledge “that climate change impacts are often transboundary in nature and may involve complex, cascading risks that require knowledge-sharing and international cooperation for addressing them.”Footnote ⁶⁹ In fact, the agreement devotes an entire section to “International Cooperation,” recognizing “the importance of international cooperation, including transboundary cooperation, for contributing to progress towards the goals of the Paris Agreement.”Footnote ⁷⁰

At COP29 in 2024, states established a new climate finance goal to increase the scale of international assistance to developing countries from the previous goal of USD 100 billion annually to 300 billion annually by 2035.Footnote ⁷¹ At COP30, in 2025, governments have committed to present new NDCs that are “economy-wide, cover all greenhouse gases and are fully aligned with the 1.5°C temperature limit.”Footnote ⁷² On our view, states bear a legal obligation to both their people and humanity to advance these goals through good faith cooperation. We consider now the argument in favor of viewing their cooperation as mandatory.

Recalcitrant States

Arguably, the international community has elected to place climate change policy under joint stewardship precisely because a healthy global environment is a non-excludable public good, and so the reduction of GHG pollution and adaptation poses a serious collective action problem. Self-interested states would prefer to free ride, letting others bear the cost of mitigation measures, while they themselves avoid those costs while benefitting from a relatively healthy environment. The logic of the prisoner’s dilemma encourages states to pursue their narrow self-interest, since whether or not other states shoulder the burden of climate mitigation, a state will typically do better economically by avoiding the burden. But, of course, if a plurality of heavily polluting states adopted this policy, climate mitigation would be severely threatened if not doomed. The mandatory cooperation of the Paris Agreement and Glasgow Pact addresses this collective action problem by providing a framework for joint stewardship that makes the development and implementation of NDCs transparent, with the hope that national policymakers may be held accountable. Of course, this approach depends on policymakers caring about climate change and the Agreement’s multilateral process, or at least caring about the consequences of refusing to participate in good faith. The quality of states-parties’ participation in the COP/CMA framework, their ability to reach consensus on deeply contentious and high budget matters, and their public commitment to the goals of mitigation and adaptation suggest that, in general, most states at most times care a lot about climate change and want to be known as good global climate actors. But, regrettably, not all states at all times.

Pursuant to his “America First” policy, US President Donald Trump indicated early in his first term that the United States would withdraw from the Paris Agreement.Footnote ⁷³ Article 28 of the Agreement provides that a party may give notice of withdrawal “any time after three years from the date on which the Agreement has entered into force” for that party, but the withdrawal takes effect only one year after notification.Footnote ⁷⁴ The United States submitted its withdrawal notification on November 4, 2019, and formally withdrew from the Paris Agreement on November 4, 2020, one day after the presidential elections in which Joseph Biden prevailed. Withdrawal made the United States a free rider on the mitigation efforts of others, and was a brazen assertion of unilateralism in breach of the United States’ joint stewardship obligations. The assertion was especially brazen because, as noted, the Paris Agreement does not subject states-parties to emission-reduction quotas or targets. States must merely develop some climate change mitigation policy in nonbinding (but good faith) negotiations with others and subject the policy’s implementation to public review. Withdrawal from the Paris Agreement was therefore an outright rejection by the United States of international legal norms requiring mandatory cooperation in the field of climate change. This jeopardized collective action on the environment, in part because the United States is one of the world’s largest carbon emitters, and in part because defections from collective action regimes and open free riding breed resentment and may prompt further defections.

The United States’ withdrawal did not have grave practical implications in the short term because the Biden administration signaled during and immediately after the 2020 election that it would rejoin the Paris Agreement.Footnote ⁷⁵ Nonetheless, upon his return to the White House in January 2025, President Trump initiated a second US withdraw from the Paris Agreement,Footnote ⁷⁶ potentially prompting other states to follow.Footnote ⁷⁷ It is worth reflecting, therefore, on whether a recalcitrant state is entitled to go it alone and do as it pleases with respect to climate policy.

We suggest that the substantive and procedural norms of mandatory cooperation are binding independent of their codification in the Paris Agreement or the Glasgow Pact. The rationale for the theory proceeds from the premise that states’ GHG emissions spill over into the global atmosphere possessed in common by all. As discussed in Chapter 6, transboundary environmental harm triggers duties of mandatory cooperation, such as duties to share information, negotiate in good faith, demonstrate due regard for other states and their nationals, and reduce harm where practicable.Footnote ⁷⁸ In the climate change context, where transboundary pollution harms all states, the duties of mandatory cooperation become omnilateral. A practical way to specify and satisfy these duties within a regime that respects sovereign equality and avoids unilateralism is to authorize states to serve as coequal joint stewards of the atmosphere within an institutional framework such as the UNFCCC. For this charge to be legally meaningful, states must have some obligation to take it seriously.

The legal obligation to cooperate with other states in addressing the harmful effects of climate change derives in part from the issue’s long-standing status under the UNFCCC, the Convention on Biodiversity, the Paris Agreement, and the Glasgow Pact as a “common concern of humankind.” This status is evidence of a customary rule that states have an obligation to work together in good faith to mitigate climate change because the environment is an important and nonexcludable public good on which humanity depends. Further evidence of such a customary rule is discernible from the relationship between a state and its people, on the one hand, and the state and humanity, on the other. As fiduciaries of their people and joint stewards of humanity, states owe both their people and humanity an obligation to do what is reasonably necessary to safeguard the environment. Because climate change is quintessentially a collective action problem, addressing it effectively necessarily requires states to negotiate mitigation and adaptation measures together in good faith.

Mandatory cooperation in a context in which the United States has withdrawn from the Paris Agreement would require the United States to take good faith steps to mitigate climate change and provide for adaptation. The United States would enjoy wide discretion to design and implement mitigation measures, much as states-parties to the Paris Agreement enjoy broad authority over the development and implementation of NDCs. The United States would also, however, be under an obligation to exercise that discretion in a way that did not subvert the collective mitigation efforts of other states, and in a manner that demonstrated due regard for other states touched by its GHGs. In addition, mandatory cooperation would entail procedural obligations of investigation, consultation, negotiation, and possibly third-party dispute resolution. Thus, even if the United States were to again withdraw from the Paris Agreement, and for a lengthier duration, it may still be bound by substantive and procedural customary norms of mandatory cooperation that call on the United States to have due regard for the environmental interests of other states, including Kiribati and others suffering climate harms now.

This again raises the question of compliance. What if the United States withdraws and explicitly refuses to recognize the validity or applicability of any international legal obligations in this sphere? Such a move could have far-reaching, and potentially disastrous consequences for global efforts to combat climate change. Purely as a conceptual matter, however, the compliance problem does not appear any more or less pressing here than in other areas of international law. Moreover, issues of compliance go to states’ motivations for complying with international norms and the likelihood of their compliance with them, whereas our project has been to theorize norms that are already part of international legal practice. While practical concerns counsel publicists to take compliance seriously, elaborating the nature and implications of legal principles, as we have tried to do, is a separate inquiry.

A further issue raised by the prospect of customary norms of mandatory cooperation concerns whether the persistent objector doctrine would apply, such that unwilling states can legally opt out of multilateral regimes. In our view, these states would be in the same legal position as states that attempt to negotiate a settlement of a dispute in good faith but simply cannot reach amenable terms with the counterparty. Like these states, persistent objectors would remain subject to norms that prohibit them from adopting measures or positions that undermine the efforts of other states to develop an equitable multilateral framework. They would also remain subject to the obligation to continue to pursue good faith efforts to reach a mutually acceptable outcome. We recognize that, as a general matter, holding states to a customary obligation to seek third-party dispute resolution over climate change mitigation measures might appear, at this point in the evolution of international law, more prescription than description. However, it is a prescription wholly consonant with the principles of sovereign equality and joint stewardship that underlie mandatory cooperation’s other norms. And, as we explain now, it is also a prescription that international courts and tribunals appear ready to endorse, just as they have affirmed duties of mandatory cooperation for other matters of international concern, such as maritime delimitation and transboundary pollution.

Adjudicating Climate Change Mitigation

Within the past several years, international courts and tribunals have received several requests for advisory opinions on states’ international obligations concerning climate change mitigation. In December 2022, the Commission of Small Island States on Climate Change and International Law (COSIS), an organization that represents climate-vulnerable states like Kiribati, requested an advisory opinion from the International Tribunal for the Law of the Sea (ITLOS).Footnote ⁷⁹ COSIS asked the tribunal to specify states’ obligations to preserve and protect the marine environment under the UN Convention on the Law of the Sea (UNCLOS) in light of the deleterious impact of GHGs on the global climate.Footnote ⁸⁰ A month later, Chile and Colombia requested that the Inter-American Court of Human Rights (IACtHR) prepare an advisory opinion concerning states’ climate-related obligations under the American Convention on Human Rights.Footnote ⁸¹ The request for an advisory opinion specifically invited the Court to clarify, inter alia, states’ “cooperative obligations” for mitigating climate change.Footnote ⁸² On March 29, 2023, the UN General Assembly adopted resolution 77/276 with the support of 150 states, requesting an advisory opinion from the ICJ on “the obligations of States under international law to ensure the protection of the climate system and other parts of the environment from anthropogenic emissions of greenhouse gases for States and for present and future generations.”Footnote ⁸³ Within just four months, these requests for advisory opinions vaulted states’ obligations with respect to climate change to the center stage of international adjudication.

The ITLOS tribunal, the IACtHR, and the ICJ have now delivered landmark advisory opinions concerning climate change. The ITLOS tribunal unanimously affirmed that states-parties to UNCLOS bear duties to “prevent, reduce, and control” the emissions that contribute to oceanic warming and acidification.Footnote ⁸⁴ States’ duties to curb GHGs are not limited to their voluntarily determined contributions under the Paris Agreement; to satisfy UNCLOS, states must “take all necessary measures to prevent, reduce and control marine pollution from anthropogenic GHG emissions, including measures to reduce such emissions.”Footnote ⁸⁵ The measures states take to prevent, reduce, and control GHG emissions must be reasonably calculated to protect the marine environment, consistent with the requirement of due diligence under customary international law.Footnote ⁸⁶

Significantly, the ITLOS tribunal also offered a resounding endorsement of mandatory cooperation for climate change mitigation. The tribunal emphasized that “the duty to cooperate is a fundamental principle in the prevention of pollution of the marine environment under [both UNCLOS] and general international law.”Footnote ⁸⁷ The “core” of this obligation, the tribunal explained, is states’ duty to cooperate in “developing a common regulatory framework ‘for the protection and preservation of the marine environment.’”Footnote ⁸⁸ Under UNCLOS, states must “endeavour to harmonize” their regulatory responses to climate change, exercising “stringent” due diligence to adopt common rules, standards, and recommended practices and procedures to protect and preserve the marine environment from the adverse impacts of GHGs.Footnote ⁸⁹ Due diligence requires states to expend substantial effort, consult with one another in good faith,Footnote ⁹⁰ and cooperate in undertaking and promoting scientific research and exchanging information and data about oceanic pollution.Footnote ⁹¹ Perhaps most striking, the tribunal declared that these obligations of mandatory cooperation are not fully exhausted by the UNFCCC and the Paris Agreement:

Thus, mandatory cooperation may require the international community to take more aggressive measures now and in the future to prevent, reduce, and control the escalating impacts of GHGs on the global environment.

The advisory opinions of the IACtHR and the ICJ were released as this book went to press and go further still. Linking state obligations to address climate change to human rights enshrined in the American Convention of Human Rights, the IACtHR frames its analysis as responding to “the climate emergency” of “climate change, pollution, and biodiversity loss.”Footnote ⁹³ Breaking new ground, the IACtHR finds that states are subject to a peremptory or jus cogens norm of international law to safeguard humanity against “anthropogenic conducts with irreversible impacts on the vital equilibrium of the planetary ecosystem,” since these conducts “undermine the conditions required sine qua non for the enforceability of fundamental human rights that are already protected under international law by peremptory provisions.”Footnote ⁹⁴ Further, the IACtHR dedicates a lengthy section to “The Obligation of Cooperation,” finding that “[t]he obligation of States to cooperate in good faith forms part of customary international law” and that “cooperation is a cardinal principle established in the OAS Charter.”Footnote ⁹⁵ The Court observes that, as a general matter, “the obligation of cooperation has special relevance in all contexts in which the international community pursues common objectives or faces problems that require collective solutions,” and that this is “precisely the case in relation to addressing the causes and impacts of climate change.”Footnote ⁹⁶

The ICJ’s Advisory Opinion is likewise unequivocal in its prescription of mandatory cooperation to address climate change.Footnote ⁹⁷ The Court observes at the outset that states-parties to the UNFCCC, the Kyoto Protocol, the Paris Agreement, UNCLOS and other environmental treaties have interlocking treaty-based obligations of mitigation and adaption to address climate change.Footnote ⁹⁸ The ICJ also finds that states have a duty under customary international law “to prevent significant harm to the environment” that applies “to global environmental concerns.”Footnote ⁹⁹ And, just as significantly, the Curts affirms “that the duty of States to co-operate for the protection of the environment is a rule whose customary character has been established.”Footnote ¹⁰⁰ Emphasizing the customary status of the duty to co-operate, the Court notes that the “duty to co-operate is intrinsically linked to the duty to prevent significant harm to the environment, because unco-ordinated individual efforts by States may not lead to a meaningful result.”Footnote ¹⁰¹ The customary duty to cooperate “is applicable to all States,” the Court says, although its demands are sensitive to “the common but differentiated responsibilities and respective capabilities principle.”Footnote ¹⁰² The customary duty applies “regardless of whether a State is a party to the climate change treaties.”Footnote ¹⁰³ The ICJ concludes that “[c]o-operation is not a matter of choice for States but a pressing need and a legal obligation.”Footnote ¹⁰⁴

Conclusion

It is far beyond the remit of this chapter to offer a forecast of our climate future. However, let us return for a moment to Kiribati, the “canary in the coal mine.”Footnote ¹⁰⁵ Should the worst or even the fairly bad come to pass in the near future, the world will have to choose between very costly adaptation measures or providing space and status elsewhere for a people who will have become climate refugees.Footnote ¹⁰⁶ For now, the President of Kiribati, Taneti Maamau, seeks funding from developed countries “in the billions” to physically raise some portion of Kiribati’s land mass to escape the encroaching sea.Footnote ¹⁰⁷ “The wealthy countries are after all responsible for what we are facing,” President Maamau says.Footnote ¹⁰⁸ Whether developed countries step up may depend, in part, on whether they recognize and embrace their obligation to cooperate on fair terms as joint stewards of the environment.

At the Brink of Doomsday

In April 2018, an extraordinary initiative was launched in western Antarctica: the International Thwaites Glacier Collaboration (ITGC). The Thwaites Glacier is 3,900 feet thick, has a surface area equivalent to Great Britain, and is teetering on the brink of collapse due to global warming. Since the turn of the century, the glacier has lost over a billion tons of ice to the adjacent Amundsen Sea. With warming waters undermining the glacier’s outer tongue from below and cracks expanding across its surface, scientists anticipate that the glacier could shatter like a broken windshield within the next five years. When this happens, it is expected to release thousands of towering icebergs into the Southern Ocean, causing global sea levels to rise by as much as twenty-six inches. If the glacier’s collapse destabilizes neighboring glaciers, it could trigger a chain reaction of accelerated ice flow that would elevate sea levels by up to ten feet by the end of the century, with catastrophic consequences for coastal communities around the world. Seeking to better understand these potential dangers, the ITGC has assembled over a hundred scientists from seven countries to study the glacier using overflight imaging, seismometers, radar, ocean gliders, drill-implanted sensors, and submersible semi-autonomous probes. Researchers anticipate that technologies developed for the ITGC might eventually be used by national space agencies in the search for extraterrestrial life on Europa, Jupiter’s ice-encrusted, oceanic moon. For now, however, the international community has more pressing concerns: determining how much time remains before this aptly nicknamed “Doomsday Glacier” inflicts a global sea level crisis.Footnote ¹

Located in a remote sector of western Antarctica that has yet to be claimed by any country, the Thwaites Glacier is effectively the last unclaimed land on earth. The legal status of the rest of Antarctica is hotly contested. Over the past two centuries, dozens of states have sent expeditions to Antarctica, often with the purpose of establishing or fortifying claims to territorial sovereignty. Some national claims to Antarctic territory overlap with other states’ claims. To complicate matters further, two powerful states with permanent research stations in Antarctica – Russia and the United States – have refrained from asserting territorial claims but have reserved the right to do so in the future. Meanwhile, other states universally reject the territorial partition of Antarctica, insisting that the international community should instead work together through international institutions to preserve the continent’s fragile natural environment.

This unresolved controversy has been placed on hold for the time being by the Antarctica Treaty of 1959 and associated instruments – known collectively as the “Antarctic Treaty System” (ATS).Footnote ² The ATS safeguards Antarctica as a demilitarized and environmentally protected preserve for scientific study through at least 2048.Footnote ³ Legal scholars and political scientists tend to characterize the ATS as a pragmatic modus vivendi that appeals to states-parties’ rational self-interest – that is, their shared concern for avoiding armed conflict and facilitating scientific cooperation.Footnote ⁴ As this chapter will show, however, the ATS also reflects legal requirements enshrined in the UN Charter obligating states to respect sovereign equality and resolve territorial disputes through peaceful cooperation rather than the use of force. In Antarctica, states cooperated to freeze the status quo and promote scientific expeditions pending development of a permanent and comprehensive legal framework to resolve the continent’s disputed status. The ATS thus offers an important case study, illustrating how mandatory cooperation applies to territorial disputes even in the absence of a foreseeable permanent resolution.

This chapter also surveys other settings in which states are legally obligated to cooperate with one another to administer territory in accordance with equitable principles. Some territorial disputes do not implicate duties of mandatory cooperation because international law supplies a dispositive rule of decision or assigns decision-making authority exclusively to one party. For example, Bolivia v. Chile (discussed in Chapter 4) affirms that states are free to rebuff foreign offers to annex their territory.Footnote ⁵ When multiple states plausibly claim sovereignty over the same territory, however, international law does not authorize any single state to impose its will unilaterally; instead, states must consult with one another, share information relevant to their legal claims, and pursue a peaceful negotiated settlement or submit their dispute to arbitration or adjudication.Footnote ⁶ Mandatory cooperation also applies when territories are entrusted to the joint-stewardship of multiple states. In these contexts, pursuing cooperation in accordance with equitable principles is necessary to make sovereign equality meaningful under international law.

Res Communis

Long before the Antarctic Treaty, the international community addressed a similar territorial dispute at the opposite end of the world. Halfway between continental Norway and the North Pole in the extreme north of the Arctic Ocean lies an archipelago of rugged islands known today as Svalbard – “cold coast” in Old Norse.Footnote ⁷ Lacking pre-European indigenous people, Svalbard remained largely uninhabited until the seventeenth century when European whalers began hunting its surrounding waters for walruses and Bowhead whales.Footnote ⁸ As the populations of walruses and whales dwindled, so too did European interest in Svalbard. Norwegians and Russians continued to visit Svalbard in small numbers during the eighteenth and nineteenth centuries, but under international law the islands remained terra nullius, which is to say, outside the jurisdiction of any particular state.

In 1871, the Swedish-Norwegian government directed diplomatic notes to several European powers, expressing interest in acquiring Svalbard. Russia pushed back, demanding that the islands be preserved as “un domaine indécis.”Footnote ⁹ Through additional diplomatic exchanges, the two countries eventually agreed to preserve the status quo.Footnote ¹⁰ An 1872 treaty established Svalbard as an international commons or res communis open for exploitation but exempt from territorial acquisition. Adventurers and profit seekers of all nationalities were free to build settlements, perform scientific research, and conduct commerce.Footnote ¹¹ They could hunt seals, set fur traps, and put down mine shafts in Svalbard. The one thing they could not do under the 1872 treaty was lay claim to Svalbard on behalf of their respective sovereigns.

The res communis approach began to show its flaws at the turn of the twentieth century when coal and other valuable mineral deposits were discovered on Spitsbergen, the largest island in the Svalbard archipelago. As commercial enterprises from Europe and the United States arrived to exploit the islands’ resources, controversies over conflicting private claims to land and resources multiplied. Without any legal or institutional mechanisms for establishing or adjudicating title to property, companies and individuals were often at a loss to protect their interests from foreign encroachment. Making Svalbard an international commons turned out to be a recipe for incessant conflict, as well as enabling domination and exploitation by the most powerful commercial actors.Footnote ¹² No public or private interests in Svalbard could be fully secure while the territory lacked shared legal norms and institutions to ensure fair and equitable treatment.

Seeking to correct these deficiencies, Norway convened a series of diplomatic gatherings in Oslo between 1910 and 1914.Footnote ¹³ Norway’s representatives initially proposed to place Svalbard under an international administrative regime that would facilitate unlimited access to the islands for all states on the basis of sovereign equality.Footnote ¹⁴ When other states gave the proposal a cool reception, however, efforts to break the resulting impasse faded with the onset of World War I.

Only toward the end of the war did the Svalbard question resurface as a subject of serious international discussion. Enjoying the good will of the victorious Allies and exploiting the Bolsheviks’ eagerness to secure recognition for their new government, Norway succeeded in securing international support for its bid to annex Svalbard.Footnote ¹⁵ However, this historic achievement was subject to a major caveat: in exchange for international recognition, Norway agreed to guarantee full access to the islands for nationals of foreign treaty-parties, enabling them to hunt, fish, conduct scientific research, and exploit the islands’ natural resources on an equal playing field with Norwegians.Footnote ¹⁶ Norway also agreed to establish mining regulations and to endorse the property claims of foreign nationals who had established proprietary interests in land by virtue of their past activities.Footnote ¹⁷ In the treaty’s preamble, the states-parties expressed their hope that this framework would establish an “equitable regime” to facilitate the islands’ cooperative “development and peaceful utilisation.”Footnote ¹⁸

In sum, Svalbard’s human history reflects the territory’s transition from a res communis to an equitable regime administered under Norwegian sovereignty. States ultimately opted for a cooperative legal order that would respect equitable principles, securing their practical interests against foreign domination. For over a century, these features of the Spitsbergen Treaty have facilitated peaceful international cooperation in Svalbard.Footnote ¹⁹

Who Rules Antarctica?

Concerns for international equity and multilateral cooperation have also shaped the legal regime for Antarctica. Like Svalbard, Antarctica has transitioned from an essentially unregulated res communis to a multilateral treaty-based regime that better guarantees respect for sovereign equality. In the case of Antarctica, however, this result has been achieved not by vesting sovereign jurisdiction in a particular state or group of states, but instead by providing a framework for international cooperation and environmental stewardship without resolving the underlying territorial disputes.

The story of humanity’s engagement with Antarctica begins just two centuries ago. On January 28, 1820, one day after leading just the second maritime expedition across the Antarctic Circle, Russian naval commander Fabian Gottlieb von Bellingshausen sighted a “solid stretch of ice running from east through south to west.”Footnote ²⁰ Stretched out before his view was a vast continent roughly the size of Mexico and the United States combined.Footnote ²¹ Nearly all of Antarctica is concealed beneath an ancient ice dome that averages 6,600 feet in thickness and contains 90 percent of the world’s freshwater reserves.Footnote ²² This icy mantle gives Antarctica the highest average elevation of any continent in the world – nearly twice the median height of Asia, the world’s next highest continent. Blasted by ferocious winds, subfreezing temperatures, and total darkness during its long winter months, Antarctica ranks among the least hospitable environments for human habitation in the world.Footnote ²³ After sighting this bleak polar desert, Bellingshausen and his crew reversed course without making landfall.

Despite these extreme conditions, explorers, scientists, and sealers from around the world soon flocked to Antarctica in pursuit of adventure, profit, and glory. Some of these expeditions laid the groundwork for sponsoring states to stake claims to territorial sovereignty. Seven states would eventually lay claim to pie-slice sectors of Antarctica, beginning with the United Kingdom in 1908, followed by France, Norway, Chile, Argentina, Australia, and New Zealand.

Throughout the period of Antarctica’s early exploration, international law permitted states to claim sovereignty over terra nullius unilaterally. This rule was designed by and for European nations to enable colonialism and mediate claims between colonial powers, with little or no regard for prior indigenous occupation.Footnote ²⁴ To establish and maintain sovereignty, however, states were required to “effectively occupy” territory.Footnote ²⁵ This meant taking actual possession and making a “continuous and peaceful display of sovereignty” by establishing a permanent administration in situ to govern the territory in the name of the claimant state.Footnote ²⁶ Given the daunting challenges presented by Antarctica’s inhospitable natural environment, none of the seven claimant states attempted to establish continuous sovereign governance in Antarctica prior to asserting territorial claims.Footnote ²⁷ Instead, they argued that this was impractical and legally unnecessary to establish territorial sovereignty in the Antarctic context.Footnote ²⁸ In support of this view, claimant states would later cite Max Huber’s observation in the Island of Palmas Case (1928) that “[m]anifestations of territorial sovereignty” may vary depending on “conditions of time and place.”Footnote ²⁹ In view of Antarctica’s extreme climate, claimant states asserted that what constituted effective occupation could be relaxed in this context. Some measures that would not suffice to create or maintain sovereign title elsewhere – including discovery, exploration, proximity to sovereign territory, scientific study, the erection of physical markers, or the construction of a permanent research station – might suffice to confer sovereign rights over the continent’s expansive and largely unexplored hinterlands.Footnote ³⁰

By the mid-twentieth century, claimant states encountered three formidable obstacles to their efforts to carve up Antarctica. First, claimant states could not agree among themselves about how a flexible approach to effective occupation would apply to their Antarctic claims. For example, Argentina and Chile failed to persuade other states that large sections of Antarctica fell under their sovereignty because those sections were natural extensions of their sovereign territories in South America.Footnote ³¹ European claimants based their claims on their asserted first discovery of the sectors of the continent.Footnote ³² The United Kingdom, in particular, resisted the Argentine-Chilean claims, arguing that it had already established sovereignty over much of the same territory based on its first discovery.Footnote ³³ These divergent positions proved to be irreconcilable.

Further complicating the state of play was the possibility that other states might assert competing claims to Antarctica in the future. By the 1950s, both the Soviet Union and the United States had engaged in significant expeditions in Antarctica. Although the Soviet Union and the United States refrained from formally asserting territorial claims in Antarctica, both asserted the right to do so in the future, and their political influence posed a major deterrent against claimant states advancing their claims with greater force.

The third challenge confronting claimant states was the absence of international political or diplomatic recognition for their claims. Non-claimant states uniformly rejected Antarctic territorial claims. Legal commentators agreed that claimant states had not established the kind of effective occupation necessary to establish territorial jurisdiction.Footnote ³⁴ By the 1920s, the US government threw its weight behind the view that Antarctic claims must be accompanied by actual settlement to be effective under international law.Footnote ³⁵ Other non-claimant states argued that none of the claimants had established the kind of functioning government in Antarctica that could ground a plausible claim to effective occupation.

As long as the legal rules governing Antarctica remained unsettled, no state claim could be secure from foreign interference. This was not merely a hypothetical concern. In 1952, Argentineans at Hope Bay fired warning shots over the heads of a British group that was attempting to establish a research station in the disputed area. The following year, an Argentinean expedition erected a hut on Deception Island a short distance away from a new British base. The British Colonial Office characterized this move as an act of “aggression” against its territorial sovereignty that justified the responsive use of force in self-defense.Footnote ³⁶ The United Kingdom dispatched Falkland Islands Governor Colin Campbell aboard the H.M.S. Snipe, accompanied by fifteen marines and two police officers, to dismantle Argentina’s hut and arrest its two occupants. When news of this action reached Argentina, protests erupted in the streets of Buenos Aires.Footnote ³⁷

Skirmishes like these raised fears that Antarctica might become a flashpoint for international conflict during the second half of the twentieth century. That these fears were not realized is a testament to the power of international cooperation. During the 1950s, an era otherwise defined by bitter Cold War rivalries, Antarctic states succeeded in establishing the ATS – a multilateral regime that has facilitated peaceful scientific cooperation ever since.

The Miracle on Ice

This happy result was hardly inevitable. During the first half of the twentieth century, many proposals to resolve the Antarctica question were promoted and debated, but none was deemed acceptable to all interested states. Some advocated internationalizing Antarctica under the administration of the League of Nations or the United Nations, perhaps as a trusteeship under the UN Trusteeship Council.Footnote ³⁸ Another proposal would have placed the whole continent under a joint condominium for the collective benefit of the claimant states.Footnote ³⁹ However, some of the claimant states adamantly opposed any measures that would extinguish or dilute their asserted entitlements to territorial sovereignty.Footnote ⁴⁰

Stymied on the negotiation front, the United Kingdom on several occasions attempted to take its disputes with Argentina and Chile to the International Court of Justice (ICJ), but the South Americans repeatedly refused to cooperate in submitting a joint-application to the ICJ.Footnote ⁴¹ The United Kingdom eventually gave up and submitted a unilateral application to the Court in May 1955,Footnote ⁴² but Argentina and Chile successfully contested the ICJ’s jurisdiction, prompting the Court to remove the case from its list.Footnote ⁴³ This result reverberated beyond the instant dispute. Had the Court addressed the case on the merits, it might have clarified how the international law of territorial acquisition applied to Antarctica. Once it became clear that an authoritative statement from the Court would not be forthcoming, and with no realistic prospect that Argentina and Chile would submit to adjudication or arbitration elsewhere, the international community confronted the unsettling possibility that the international law governing Antarctica would remain unsettled indefinitely. This state of affairs cast a shadow over all claims to Antarctic territory.

At this moment of uncertainty, an ambitious scientific initiative laid the groundwork for the international community to establish a new legal regime for Antarctica. Beginning in 1950, scientists championed a plan to designate 1957–1958 as an “International Geophysical Year” (IGY) to study holistically how the earth operates as a system. With phenomena like geomagnetism, meteorology, and polar auroras featuring prominently in the IGY’s research agenda, it was evident from the start that Antarctic research would be critical to the initiative’s success. International negotiations led eventually to a simple solution: for the duration of the IGY, states would suspend their territorial disputes so that scientists from all over the world could engage in Antarctic research. Activities conducted during the IGY, including the construction of scientific research stations, would not have any bearing on preexisting territorial claims.Footnote ⁴⁴

In preparation for the IGY, the United States and the Soviet Union both established permanent bases in Antarctica. The United States placed one of these research bases – the Amundsen-Scott South Pole Station – at the South Pole itself, the strategic intersection point for all seven preexisting territorial claims. The Soviet Union established a base at the “pole of inaccessibility,” the central point of the continent where temperatures fall as low as −70 degrees Celsius.Footnote ⁴⁵ By the end of the IGY, over fifty research stations had been established in Antarctica by twelve different states.Footnote ⁴⁶

As the IGY came to a close, US President Dwight D. Eisenhower gathered representatives of the twelve IGY states in Washington, DC, to discuss building on the initiative’s success by continuing to cooperate for the peaceful, nonpolitical study of Antarctica.Footnote ⁴⁷ The discussions that followed produced the Antarctic Treaty of 1959, which entered force two years later when the final three signatories – Argentina, Australia, and Chile – deposited their instruments of ratification.Footnote ⁴⁸ Fifty-eight states have now become parties to the treaty.Footnote ⁴⁹

For an agreement that governs an entire continent, the Antarctic Treaty is remarkably short, with only fourteen brief articles. The preamble affirms that “international cooperation in scientific investigation in Antarctica” has benefited humankind, and it asserts that “it is in the interest of all mankind that Antarctica shall continue for ever to be used exclusively for peaceful purposes and shall not become the scene or object of international discord.”Footnote ⁵⁰ The centerpiece of the treaty is Article IV, which freezes Antarctic territorial claims by declaring that “[n]o acts or activities taking place while the present Treaty is in force shall constitute a basis for asserting, supporting or denying a claim to territorial sovereignty in Antarctica or create any rights of sovereignty in Antarctica.”Footnote ⁵¹ Article IV does not require claimant states to renounce their sovereignty claims, but it does not validate those claims either; it simply sets aside for the time being whether any of the claims or potential claims are effective under international law. In the meantime, the treaty opens the continent to continued scientific investigation (Article II), requires states to cooperate and share the fruit of their scientific activities (Article III), and prohibits states-parties from militarizing and nuclearizing the continent (Articles I and V). The treaty thus allows international scientific cooperation to continue apace without resolving the sovereignty controversy. In short, the Antarctic Treaty establishes Antarctica as a res communis, but rather than deploying this legal form for the sake of resource exploitation, as occurred in pre-1917 Svalbard, the Antarctic Treaty sets up a joint-stewardship regime to facilitate scientific cooperation.

Over the years, states-parties have supplemented the Antarctic Treaty with a variety of other agreements, including a convention to conserve Antarctic seals and marine living resourcesFootnote ⁵² and a comprehensive environmental protocol, known as the Madrid Protocol.Footnote ⁵³ Antarctic states have committed to guarantee “the comprehensive protection of the Antarctic environment and dependent and associated ecosystems,” thereby preserving “Antarctica as a natural reserve, devoted to peace and science.”Footnote ⁵⁴ To this end, the Madrid Protocol bans mining and drilling activities except for scientific purposes.Footnote ⁵⁵ States-parties must “co-operate in the planning and conduct of activities in the Antarctic Treaty area,” conduct environmental impact assessments for their activities, and “share information that may be helpful to other Parties in planning and conducting their activities in the Antarctic Treaty area, with a view to the protection of the Antarctic environment and dependent and associated ecosystems.”Footnote ⁵⁶ When disputes arise concerning the Protocol’s “interpretation or application,” states-parties must “consult among themselves as soon as possible with a view to having the dispute resolved by negotiation, inquiry, mediation, conciliation, arbitration, judicial settlement, or other peaceful means to which the parties to the dispute agree.”Footnote ⁵⁷ These requirements are to remain in place until at least 2048.Footnote ⁵⁸

Some scholars have characterized Antarctic cooperation as “the closest thing to a ‘world order miracle’ that the world has known.”Footnote ⁵⁹ In truth, however, under international law states had no lawful alternative other than to pursue a peaceful solution to the Antarctic sovereignty question through negotiation or third-party dispute resolution.Footnote ⁶⁰ Concerns of national self-interest also supported this result. It was not apparent at the time that claimant states stood to gain much from attempting to enforce their territorial claims unilaterally. Antarctica’s natural resources were largely unknown, concealed beneath two kilometers of ice. Moreover, pressing Antarctic territorial claims would mean risking confrontation with the two global superpowers, the Soviet Union and the United States, which threatened to assert their own claims. Thus, at the time states concluded the Antarctic Treaty, both international law and concerns for national self-interest supported moving territorial claims to the back burner so that scientists could conduct research on the continent.

The Antarctic “miracle” of peaceful cooperation has been replicated in some other contexts, from the Beaufort Sea controversy between Canada and the United StatesFootnote ⁶¹ to the pending case in the ICJ between Gabon and Equatorial Guinea over islands in the Gulf of Guinea.Footnote ⁶² Even some bitter enemies have managed to handle territorial disputes through cooperation. For example, India and Pakistan have committed to manage their acrimonious contest over Kashmir in accordance with the UN Charter “through bilateral negotiations or by any other peaceful means mutually agreed upon between them,” respecting “each other’s national unity, territorial integrity, political independence and sovereign equality.”Footnote ⁶³ Under the 1972 Simla Agreement, India and Pakistan have agreed that, “[p]ending the final settlement of any of the problems between the two countries, neither side shall unilaterally alter the situation and both shall prevent the organization, assistance or encouragement of any acts detrimental to the maintenance of peaceful and harmonious relations.”Footnote ⁶⁴ Although these commitments have been sorely tested by a limited war in 1999, sporadic violence along the border that continues into the present, and political maneuvering on both sides, thus far the legal framework of mandatory cooperation has prevented hostilities between India and Pakistan from spiraling out of control. Ultimately, international law and national self-interest have combined in these settings to promote international peace and security.

Granted, it is not realistic to expect that states will always respect their legal obligations to manage territorial disputes peacefully through negotiation or third-party dispute resolution. Too often, states assert the prerogative to determine their own borders unilaterally. Beyond Russia’s controversial annexation of Crimea in 2014 (discussed in Chapter 1), prominent examples of unilateral territorial settlement include Azerbaijan’s occupation of the Nagorno-Karabakh region, Israel’s expanding settlements in the West Bank, and Morocco’s longstanding presence in Western Sahara. Territorial settlements like these reproduce the wrongs of colonialism: states claim territorial sovereignty unilaterally without regard to the rights and legitimate interests of indigenous political communities. Unilateral territorial settlement essentially treats disputed territories as res nullius, ignoring the principle of sovereign equality and the right to self-determination under contemporary international law. Mandatory cooperation outlaws this form of neocolonialism. Whenever states delimit their shared borders on land or at sea, they must resolve disputes through negotiation or third-party dispute resolution in accordance with equitable principles.Footnote ⁶⁵ Although embittered rivals cannot always be convinced to meet at the negotiating table or submit their disputes to arbitration or adjudication, international law nudges them in that direction by denying legal validity and legitimacy to territorial settlements achieved through unilateral action such as aggression and occupation.

Internationalization

Mandatory cooperation also applies when states internationalize territory. A territory is considered to have been “internationalized” when it is removed from national jurisdiction, in whole or in part, in favor of international administration.Footnote ⁶⁶ During the twentieth century, states experimented with internationalization in a variety of settings, with mixed success. For example, at the conclusion of World War I, the Allied Powers designated the port city of Danzig (currently Gdańsk) as an independent “Free City.”Footnote ⁶⁷ From its establishment in 1920 until the Nazi annexation of 1939, Danzig enjoyed local democratic government subject to the League of Nations’ authority to supervise the city’s administration and guarantee compliance with its Constitution.Footnote ⁶⁸ In virtue of Danzig’s internationalized status, members of the League of Nations were legally obligated to cooperate with efforts to guarantee the city’s autonomous legal status and government.

Unlike the internationalization of Danzig, most exercises in international territorial administration have been designed as temporary solutions to aid conflict resolution, protect human rights, and pave the way for national self-determination. For instance, the Mandate System of the League of Nations authorized selected states to serve as “Mandatories of the League” in administering territories that had been wrested from Germany and the Ottoman Empire during World War I.Footnote ⁶⁹ The UN Charter later replaced the Mandate System with a Trusteeship System that commissioned some states to administer former mandates and colonial holdings of the defeated Axis Powers.Footnote ⁷⁰ Subsequently, the Security Council has authorized the Secretariat to conduct territorial administration on an ad hoc basis in countries such as Cambodia (1992–1993), Somalia (1993–1995), Eastern Slavonia (1996–1998), East Timor (1999–2002), and Kosovo (1999–present).Footnote ⁷¹ Across these and other contexts, international law requires states to cooperate with one another and with international organizations to ensure the success of international territorial administration.Footnote ⁷²

Between the Moon and the Deep Blue Sea

Within the past half century, technological advances have opened new frontiers for human exploration and exploitation. From the deep ocean floor to the surface of the moon, it is now possible to imagine humanity exploiting natural resources in environments that were previously inaccessible. These developments raise important legal questions. Are such spaces terra nullius subject to national acquisition? Should they be understood as an international commons or res communis similar to the high seas or Svalbard at the turn of the twentieth century – that is, subject to exploitation but not state sovereignty? Should the international community entrust these spaces to international institutions? Or would a different legal regime be preferable?

In 1963, the UN General Assembly addressed some of these issues in a Declaration of Legal Principles Concerning the Activities of States in the Exploration and Use of Outer Space.Footnote ⁷³ “Desiring to contribute to broad international cooperation in the scientific as well as in the legal aspects of exploration and use of outer space for peaceful purposes,” the General Assembly “[s]olemnly declare[d] that in the exploration and use of outer space States should be guided by the following principles”:

1. 1. The exploration and use of outer space shall be carried on for the benefit and in the interests of all mankind.

2. 2. Outer space and celestial bodies are free for exploration and use by all States on a basis of equality and in accordance with international law.

3. 3. Outer space and celestial bodies are not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.

4. 4. The activities of States in the exploration and use of outer space shall be carried on in accordance with international law, including the Charter of the United Nations, in the interest of maintaining international peace and security and promoting international cooperation and understanding.Footnote ⁷⁴

Through these principles, the General Assembly envisioned a new legal paradigm for outer space territory and resources. Like Svalbard in the late-nineteenth and early-twentieth centuries, resources in outer space would be “free for exploration and use” by all states without being subject to national appropriation. Unlike Svalbard, however, states would not be permitted to exploit resources in outer space exclusively for their own national gain. Any activities conducted in outer space would have to “be carried out for the benefit and in the interests of all mankind.”Footnote ⁷⁵

A few years later, these principles were incorporated into the “Magna Carta of space law”Footnote ⁷⁶ – the Outer Space Treaty of 1967.Footnote ⁷⁷ The Outer Space Treaty declares “outer space, including the Moon and other celestial bodies,” to be “the province of all mankind.”Footnote ⁷⁸ It affirms that outer space resources are “not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.”Footnote ⁷⁹ Like the General Assembly principles, it also authorizes states to engage in “free … exploration and use” of outer space resources on the basis of equality, while emphasizing that that these activities “shall be carried out for the benefit and in the interests of all countries, irrespective of their degree of economic or scientific development.”Footnote ⁸⁰ As of January 2025, the Outer Space Treaty has 116 states parties.Footnote ⁸¹

International lawyers have debated what it means for states to explore and use the moon and other celestial bodies “for the benefit and in the interests of all countries,” as required under the Outer Space Treaty. Some argue that resources harvested from outer space are the “common heritage of mankind” and therefore must be shared equitably with the rest of the international community.Footnote ⁸² The 1979 Moon Agreement endorses this position, declaring that resources from the moon are subject to “equitable sharing by all States Parties,” including developing countries.Footnote ⁸³ The Moon Agreement’s legal authority is limited, however, by the fact that only seventeen states have ratified it and few states have accepted its contents as expressive of customary international law.Footnote ⁸⁴ Some other international lawyers contend that the Outer Space Treaty declares space resources to be “the province of mankind” only with respect to “exploration and use,” not exploitation. On this interpretation, outer space is a res communis comparable to the high seas, where states are free to take resources without sharing the benefits with other states as long as they respect other states’ freedom to do likewise.Footnote ⁸⁵ An intermediate view is that states are obligated to share benefits derived from their activities in outer space but it is up to them, and them alone, to determine how to do so in accordance with equitable principles.Footnote ⁸⁶

Regardless of how the international community defines the “common province of mankind,” it is clear that the concept activates legal duties of international cooperation. States with active space programs cannot respect sovereign equality without recognizing the equal right of other states to explore, use, and benefit from outer space. At a minimum, this means that states may not interfere arbitrarily with other states’ peaceful space programs. But the requirements of mandatory cooperation do not end there: states must also notify and consult with one another about their space activities, share information, render assistance, and seek to resolve disputes through peaceful cooperation. In this spirit, the Outer Space Treaty requires states-parties to practice “cooperation and mutual assistance” and “conduct all their activities … with due regard to the corresponding interests of all other States Parties.”Footnote ⁸⁷

The “common heritage of humanity” concept has achieved broader acceptance in another area: the deep seabed. In 1966, US President Lyndon Johnson gave a speech in which he argued that “the prospects of rich harvest and mineral wealth” from the deep seafloor should not be allowed “to create a new form of colonial competition among maritime nations … We must ensure that the deep seas and ocean bottom are, and remain, the legacy of all human beings.”Footnote ⁸⁸ A year later, Maltese Ambassador Arvid Pardo echoed these sentiments in a celebrated address to the General Assembly, proposing that resources in the deep seabed be recognized as the common heritage of humanity.Footnote ⁸⁹ The General Assembly unanimously endorsed this proposal in 1970, declaring the deep seabed the common heritage of humanity and therefore not subject to national appropriation. To facilitate the seabed’s exploitation, the General Assembly called for an international regime that would “ensure equitable sharing by States in the benefits derived therefrom.”Footnote ⁹⁰ All of these elements of Part XI of the General Assembly’s proposal would later be incorporated into the 1982 UN Convention on the Law of the Sea (UNCLOS).Footnote ⁹¹ Once the international community designated the deep seabed as the common heritage of humanity – a resource vested in humanity “as a whole” and exempt from national appropriation – the necessary consequence was that states were obligated to cooperate with one another to achieve mutually acceptable solutions in accordance with equitable principles.

One final example of common heritage resources deserves special mention: cultural heritage sites. Under contemporary international law, significant cultural sites and natural wonders, such as India’s Taj Mahal, the Great Wall of China, and Victoria Falls in Zambia/Zimbabwe, are governed by a series of international agreements that include UNCLOSFootnote ⁹² and various treaties adopted under the auspices of the UN Educational, Scientific, and Cultural Organization (UNESCO).Footnote ⁹³ These conventions require states not only to protect cultural heritage sites, but also to cooperate with one another for this purpose, suggesting that the preservation of cultural heritage is a joint-stewardship responsibility of the entire international community.Footnote ⁹⁴ Duties to cooperate in preserving cultural heritage do not deprive states of their sovereign authority over sites within their territory. Instead, they constrain how national authorities may exercise their sovereign rights over cultural heritage sites to ensure that they fulfill their joint-stewardship responsibilities and respect the interests of humanity as a whole. In this sense, states’ duties to cooperate for the preservation of cultural heritage sites are similar to the equitable obligations that govern international rivers (see Chapter 2) and landlocked states (see Chapter 4).

Looking to the Future

Each of the case studies discussed in this chapter reflect a transition from legal frameworks involving unilateral state action (e.g., terra nullius, unregulated res communis) to legal frameworks that require multilateral cooperation (e.g., agreements guaranteeing equitable use and apportionment of resources). In Antarctica, states embraced multilateralism, in part, because international law did not permit them to resolve disputed claims or potential future claims unilaterally. Given the serious uncertainty over what constitutes effective occupation for Antarctica, no state could establish its territorial sovereignty unilaterally without violating the principle of sovereign equality. A lawful and legitimate solution to the Antarctica controversy therefore required cooperation. Similarly, once the international community designated the moon and other celestial bodies, the deep seabed, and cultural heritage sites as common concerns of humanity, it followed that states were required to cooperate with one another to regulate these spaces in accordance with equitable principles.

Time will tell whether this shift in international law is durable. A common characteristic of Antarctica, the deep seabed, and the moon is that they are all extreme environments where the commercial exploitation of natural resources is not yet financially viable on a large scale. As technology advances, humanity may well face conditions that invite a new colonial era of unilateralism at the South Pole, on the ocean floor, or in outer space. With the ATS’s expiration date on the horizon and global warming exposing more of the continent and its surrounding waters to drilling and mining, the future of Antarctica hangs in the balance. If states simply allow the ATS to lapse without replacing it with a new legal framework, this could spark a race to establish territorial control through unilateral displays of force and occupation, undermining international peace and security. Alternatively, the international community could pursue other options that would better respect sovereign equality under international law. For example, claimant states could cooperate with non-claimant states to recognize Antarctica as the common heritage of humanity, designating it as a “world park” under the administration of an international organization. This is the preferred outcome of the Organization of African Unity and G-77 developing states.Footnote ⁹⁵ Whatever the future holds, the key point for present purposes is that international law obligates states to resolve the Antarctic sovereignty question through peaceful cooperation in accordance with equitable principles.

The Federation of the World

On June 25, 1945, a hulking C-54 military transport plane descended through foggy skies to touch down at Hamilton Airforce Base north of San Francisco. Waiting on the tarmac were US Secretary of State Edward Stettinius, California Governor Earl Warren, and the heads of forty-nine foreign delegations from around the world.Footnote ¹ As a military guard saluted and a brass band played, US President Harry Truman emerged from the plane wearing a grey double-breasted suit, a blue bowtie, and an exultant smile. Although war with Japan raged on in the Pacific, Truman’s spirits were high, and for good reason. He had come to witness the birth of a new world order – one intended to end war for generations to come.

Nine weeks earlier, diplomats and heads of state had gathered in San Francisco at the invitation of Truman’s predecessor, Franklin Roosevelt, with an ambitious goal: to lay the foundation for a peaceful postwar order.Footnote ² Almost overnight, the City by the Bay cast aside years of wartime austerity, exchanging food rationing and blackouts for decadent parties awash with light and music, where foreign diplomats rubbed shoulders with Hollywood stars. Reporters from around the world descended in record numbers, including the young Navy hero and future US president, John Kennedy. While the press flocked to the conference’s plenary sessions at the stately San Francisco Opera House, the most consequential proceedings took place across town in Secretary Stettinius’s penthouse suite at the Fairmont Hotel on Nob Hill.Footnote ³ Representatives of the “Big Five” – China, France, the Soviet Union, the United Kingdom, and the United States – met daily to hammer out the final details of a plan, announced two years earlier in Moscow, for “a general international organization, based on the principle of sovereign equality of all peace-loving states, and open to membership by all such states, large and small, for the maintenance of international peace and security.”Footnote ⁴

Truman championed the conference’s agenda. From his youth, Truman had carried in his wallet a folded copy of several stanzas from a favorite poem by Lord Tennyson that envisioned international cooperation fostering a more peaceful world:

In the months preceding the San Francisco Conference, Truman had urged his compatriots to embrace this vision of a “Federation of the world” as the formula for enduring peace and security.Footnote ⁶ “The policy we hope and believe will emerge from the San Francisco Conference and others to follow will embody cooperation among nations to keep down aggressors,” he explained to an audience in his home state of Missouri. “The only rational alternative to existing anarchy lies in some reasonable form of international organization among so-called sovereign states.”Footnote ⁷

Thus, it was with great excitement that Truman arrived in San Francisco to join the final sessions of the conference. After greeting the assembled dignitaries, Truman led a motorcade of nearly a hundred limousines flanked by motorcycle police across the Golden Gate Bridge, where 500,000 residents – the largest crowd in the city’s history – gathered to cheer on the procession.Footnote ⁸ Later that evening, thousands packed into the Opera House to see the fifty national delegations rise from their seats to adopt the Charter of the United Nations unanimously.Footnote ⁹

The following day, as delegates reassembled for the Charter’s signing ceremony, the conference’s secretary-general, Alger Hiss, praised the participants for changing the course of history. He reminded them that the Charter affirms the proposition that “we all have to recognize – no matter how great our strength – that we must deny ourselves the license to do always as we please … This is the price which each nation will have to pay for world peace.”Footnote ¹⁰ Truman then rose to underscore the importance of international cooperation to ensure the venture’s ultimate success. He declared: “We have tested the principle of cooperation in this war, and we have found it works.”Footnote ¹¹

Eighty years later, the Charter’s ambitious framework for international cooperation remains formally intact, but its promise only partly fulfilled.Footnote ¹² Mandatory cooperation under the Charter entails essentially the same legal requirements as in other domains where it arises: states must consult, evaluate risks, share relevant information, and pursue peaceful dispute resolution with one another. When threats to peace and security emerge, states must cooperate through the United Nations to keep “a fretful realm in awe.” In addition, states must work together to address the root causes of human immiseration which undermine international peace and security, including atrocity crimes and global poverty. If the United Nations has struggled to deliver international peace and security and universal respect for human rights, the fault lies in large measure with states that have defaulted on their obligations of mandatory cooperation.

Uniting for International Peace and Security

Just as international cooperation at the San Francisco Conference gave birth to the United Nations, the Charter relies on international cooperation “to save succeeding generations from the scourge of war” and to “reaffirm faith in fundamental human rights, in the dignity and worth of the human person,” and “in the equal rights of men and women and of nations large and small.”Footnote ¹³ In the Charter’s preamble, UN member states express their determination “to practice tolerance and to live together in peace with one another as good neighbours.”Footnote ¹⁴ Article 2(4) obligates them to “refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.”Footnote ¹⁵ When international disputes arise, states must strive “in good faith” to resolve their differences “by peaceful means in such a manner that international peace and security, and justice, are not endangered.”Footnote ¹⁶ These requirements of mandatory cooperation safeguard the sovereign equality of individual UN member statesFootnote ¹⁷ while also attending to the international community’s collective interest in preserving a peaceful world order.Footnote ¹⁸

Recognizing that states might be tempted to violate these obligations, the Charter establishes the United Nations as a secondary guarantor of international peace and security. The preamble conveys the international community’s aspiration “to unite our strength” to preserve the peace, thereby ensuring “that armed force shall not be used, save in the common interest.”Footnote ¹⁹ To this end, Article 1 specifies four general purposes of the United Nations:

The Charter tasks the Security Council with coordinating the United Nations’ efforts to preserve international peace and security.Footnote ²¹ Some of the Security Council’s powers relate to encouraging states to settle their disputes through peaceful cooperation. For example, the Security Council may call upon states to embrace negotiation, mediation, conciliation, arbitration, adjudication, or other peaceful means of dispute resolution.Footnote ²² If these efforts fail, states must refer their disputes to the Security Council so that it can “recommend such terms of settlement as it considers appropriate.”Footnote ²³ The Security Council may also take action on its own initiative to investigate “any situation which might lead to international friction or give rise to a dispute, in order to determine whether the continuance of the dispute or situation is likely to endanger the maintenance of international peace and security.”Footnote ²⁴

Chapter VII of the Charter empowers the Security Council to compel recalcitrant states to take whatever steps it deems necessary to maintain international peace and security. When the Security Council identifies a threat to the peace, a breach of the peace, or an act of aggression, it may not only “make recommendations” to states but also “decide what measures shall be taken … to maintain or restore international peace and security.”Footnote ²⁵ This may include provisional measures “to prevent an aggravation of the situation” or coercive “measures not involving the use of force” (e.g., economic sanctions, travel bans).Footnote ²⁶ The Security Council may even authorize using military force to preserve or restore international peace and security (e.g., naval blockades, air strikes, peacekeeping, and peacebuilding missions).Footnote ²⁷

Significantly, the Charter obligates all states to cooperate with the Security Council’s efforts to prevent and suppress threats to international peace and security – not just those directly responsible for the threats. Under Article 25, “Members of the United Nations agree to accept and carry out the decisions of the Security Council.”Footnote ²⁸ States also pledge in Article 2(5) “to give the United Nations every assistance in any action it takes” to maintain international peace and security, as well as to “refrain from giving assistance to any state against which the United Nations is taking preventive or enforcement action.”Footnote ²⁹ States that violate these obligations expose themselves to international censure, as well as sanctions and other coercive measures, as directed by the Security Council.Footnote ³⁰ Thus, when the Security Council finds a threat to the peace or a breach of the peace, all states are obligated under the Charter to follow its lead.Footnote ³¹

In its landmark 1970 Declaration on Principles of International Law Concerning Friendly Relations and Co-operation Among States in Accordance with the Charter of the United Nations (Friendly Relations Declaration), the UN General Assembly affirmed that states bear due diligence obligations to promote the Charter’s general purposes. In particular, the Friendly Relations Declaration states that “[a]ll states shall comply in good faith with their obligations under the generally recognized principles and rules of international law with respect to the maintenance of international peace and security, and shall endeavor to make the United Nations security system based on the Charter more effective.”Footnote ³² Hence, states must settle their disputes peacefully “on the basis of the sovereign equality of States and in accordance with the principle of free choice of means” and cooperate with other states and the United Nations to maintain international peace and security.Footnote ³³

Some international lawyers might object that the Charter’s cooperative framework for collective security is undermined by Article 51, which permits states to defend themselves from attack without awaiting Security Council authorization.Footnote ³⁴ In principle, however, a state’s “inherent right” of self-defense under Article 51 is compatible with the Charter’s commitment to mandatory cooperation through the United Nations.Footnote ³⁵ Article 51 authorizes self-defense only when an actual or imminent attack has already ruptured international peace and security and only until the Security Council intercedes.Footnote ³⁶ The Charter stipulates that an act of “self-defense shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council” to prescribe a multilateral response.Footnote ³⁷ Self-defense under Article 51 is also subject to customary requirements of necessity and proportionality, which require states to consider the impact of their defensive measures on foreign interests.Footnote ³⁸ Therefore, even when states act in self-defense, international law channels their response through multilateral norms and processes to prevent states from using force “save in the common interest” to liberate humanity “from the scourge of war.”Footnote ³⁹

An Early Victory

Less than two months after the San Francisco Conference, the United Nations received an early stress test in Indonesia. On the morning of August 7, 1945 – two days after the surrender of Japan’s occupying forces – Indonesian nationalist republicans assembled at the home of their leader, Sukarno, in Djakarta. Sukarno read from a slip of paper: “We the Indonesian people proclaim the independence of Indonesia.” He then stood at attention while a simple red-and-white flag rose into the sky, asserting the birth of a new state – one that demanded independence not only from Japan but also from its British “liberators” and the Dutch colonialists who had governed before the war.Footnote ⁴⁰ Before long, hostilities broke out between Indonesia’s independence movement and British occupying forces. Meanwhile, the Netherlands readied plans for its own military action to retake the Indonesian archipelago.Footnote ⁴¹

Such were the circumstances in Indonesia in January 1946, when the Security Council gathered for its first session at Church House, its temporary London headquarters near Westminster Abbey. On the agenda were several pressing topics, including a proposal from Ukraine to address the escalating violence in Indonesia. Ukraine accused Japan and the United Kingdom of threatening international peace and security by occupying Indonesia illegally and conducting military operations against Indonesian civilians. The British vigorously disputed these charges, insisting that they had no intention of remaining in Indonesia and were simply trying to restore order and protect their troops from attack pending an orderly withdrawal.Footnote ⁴² Although the United Kingdom formally recognized Dutch sovereignty over Indonesia, British leaders attempted to prevent the Dutch from landing in Java and Sumatra and sought to broker a peaceful settlement between the Netherlands and Indonesian republicans.Footnote ⁴³

Ukraine’s proposal for Security Council action on Indonesia came up short of the necessary votes. However, when negotiations between the Netherlands and the Indonesian independence movement collapsed, prompting the Dutch to attempt to reestablish colonial rule by force, the Security Council revisited the matter at the request of Australia and India.Footnote ⁴⁴ The Netherlands, which then occupied a non-permanent seat on the Security Council, argued that the United Nations lacked jurisdiction to intercede because Indonesia fell within the Netherlands’ sovereign jurisdiction, making the issue a matter of exclusively domestic concern.Footnote ⁴⁵ No other Security Council member accepted this argument. Instead, on August 1, 1947, the Security Council, for the first time in its history, adopted a resolution demanding a ceasefire and calling on the parties to settle their dispute by arbitration or other peaceful means.Footnote ⁴⁶ Within days, both sides complied with the Security Council’s directive.Footnote ⁴⁷ The New York Times reported “that the United Nations had probably won its first major victory and through this victory had given the new international organization a sorely needed boost in prestige.”Footnote ⁴⁸

The next several years in Indonesia witnessed recurring cycles of negotiation, violent clashes, and UN-brokered ceasefires. The Security Council demanded that the Netherlands and Indonesian republicans cooperate with an international mission established to investigate and mediate their dispute.Footnote ⁴⁹ After the Security Council set a timetable for Indonesian independence, the Netherlands eventually agreed to withdraw its military and formally transferred sovereignty to the Indonesian state on December 27, 1949.Footnote ⁵⁰ International cooperation through the Security Council thus ended violent conflict and Dutch colonial rule, paving the way for international recognition of the sovereign Republic of Indonesia. On September 28, 1950, Indonesia became the sixtieth member of the United Nations.Footnote ⁵¹

Collective Enforcement in Fits and Starts

The Security Council’s engagement with Indonesia offered proof of concept that mandatory cooperation through the United Nations could perform a constructive role in maintaining international peace and security. The Security Council used various tools to achieve a peaceful settlement in Indonesia, including consultation, investigation, mediation, and legally binding resolutions. Encouraged by the preliminary results, the Security Council over the next several years applied these and other tools (albeit with mixed results) in various conflict zones, including the Balkans, Greece, Kashmir, and Palestine.Footnote ⁵² Among the Security Council’s early efforts at crisis management, however, it was the Korean War that most seriously tested the Charter’s framework for mandatory cooperation.

When North Korea invaded South Korea on June 25, 1950, it committed the kind of unprovoked aggression that the Charter’s drafters had in mind when they outlawed the “use of force against the territorial integrity or political independence of any state.”Footnote ⁵³ The United States requested a meeting of the Security Council and circulated a draft resolution condemning the North Korean attack. The draft demanded North Korea’s immediate and total withdrawal and called upon “all Member States to render every assistance to the United Nations in the execution of this resolution and refrain from giving assistance to the North Korean authorities.”Footnote ⁵⁴ With the People’s Republic of China not represented at the Security Council (the seat designated for China was occupied by Taipei rather than Beijing) and the Soviet Union boycotting the United Nations, the United States’ draft sailed through the Security Council to become Resolution 82.Footnote ⁵⁵ Two days later, the Security Council recommended that UN member states “furnish such assistance to the Republic of Korea as may be necessary to repel the armed attack and to restore international peace and security in the area.”Footnote ⁵⁶ For the first time in its history, the Security Council had invited states to defend a state under attack.Footnote ⁵⁷ By mid-September 1950, fourteen states had contributed ground forces to South Korea’s defense, and dozens of others had furnished material assistance.Footnote ⁵⁸

Whatever hopes the United States and its allies may have placed in the Security Council to rally international cooperation against North Korean aggression, the limits of this strategy soon became apparent. In Resolution 82 and subsequent resolutions, the Security Council stopped short of mandating bystander state cooperation under Articles 40–42 of the Charter. Once the Soviet Union resumed participating in Security Council meetings, its veto power prevented the Security Council from further addressing the Korean War. As a result, the Security Council lost meaningful supervisory control over South Korea’s collective defense.Footnote ⁵⁹ Just five years removed from the halcyon days of the San Francisco Conference, several of the “Big Five” states that had brought the UN Charter into the world already found themselves on opposite sides of a bloody conflict.

The incipient Cold War tensions that fueled the Korean War significantly impacted the Security Council as an institution. For the next four decades, the Security Council rarely mustered the votes necessary to respond to threats to international peace and security. However, the Security Council often invited states to cooperate in peaceful dispute resolution, and it occasionally deployed peacekeeping missions to conflict zones.Footnote ⁶⁰ For example, in the United Nations’ first formal peacekeeping mission (UNEF I), international peacekeepers helped to defuse the 1956 Suez Crisis by supervising the orderly withdrawal of British, French, and Israeli armed forces from Egypt.Footnote ⁶¹ A decade later, the Security Council, for the first time, imposed mandatory economic sanctions against Southern Rhodesia (present-day Zimbabwe) to compel its white-dominated apartheid government to relinquish power.Footnote ⁶² These measures demonstrated the United Nations’ potential to galvanize international cooperation for international peace and security. More often than not, however, hardened rivalries among the Security Council’s P5 hamstrung the Security Council’s ability to prevent and suppress violent conflicts worldwide. Perhaps the Security Council’s primary contribution during this era, therefore, was simply to foster dialogue, reducing the risks of misunderstanding and direct military confrontation among the world’s great powers.Footnote ⁶³

As relations among the P5 began to thaw in the late 1980s, the Security Council became more assertive in countering threats to international peace and security. When Iraq invaded Kuwait in August 1990, the Security Council held an emergency meeting and quickly passed a resolution ordering Iraq to withdraw “immediately and unconditionally.”Footnote ⁶⁴ Hard on the heels of this resolution came additional directives, urged by the United States and the United Kingdom but supported by most other states, declaring the annexation of Kuwait null and void, imposing a comprehensive sanctions regime on Iraq, and establishing a special committee to monitor compliance.Footnote ⁶⁵ By the end of November, the Security Council invoked its authority under Chapter VII of the Charter and gave Iraq until January 15, 1991, to withdraw from Kuwait. The Security Council authorized other states to use “all necessary means” – including military action – to expel Iraq once the deadline for voluntary withdrawal passed.Footnote ⁶⁶ Backed by the Security Council, a coalition of thirty-six nations proceeded to drive the Iraqi army from Kuwait through several weeks of aerial bombardment and an intense but brief 100-hour ground campaign.Footnote ⁶⁷

In 2003, the United States led a second military campaign against Iraq with significantly less international support. In the lead up to the war, the United States sent Secretary of State Colin Powell to the United Nations to make the case for military action to topple the regime of Saddam Hussein. Powell testified based on faulty evidence that “the facts and Iraq’s behavior show that Saddam Hussein and his regime are concealing their efforts to produce more weapons of mass destruction.”Footnote ⁶⁸ With a majority of the Security Council including Russia and France opposed to military action in Iraq, the United States, United Kingdom, and Spain abandoned last-ditch efforts to win UN backing, with British Ambassador Jeremy Greenstock advising that the trio “reserve their right to take their own steps to secure the disarmament of Iraq.”Footnote ⁶⁹ While the Security Council did not authorize military action against Iraq in 2003, it also proved incapable of thwarting two Great Powers from using military force to impose regime change and a lengthy occupation on Iraq. The Iraq War is a potent reminder that the effectiveness of the UN system depends on the willingness of its more powerful members to abide by its Charter and international law generally.

Cooperating to Respect, Protect, and Fulfill Human Rights

Since the 1990s, the Security Council has devoted increasing attention to preventing and suppressing human rights crises around the world. The groundwork for this effort was laid during the San Francisco Conference. Recall that a core purpose of the United Nations, as set forth in Article 1 of the Charter, is to “achieve international co-operation in solving international problems of an economic, social, cultural, or humanitarian character, and in promoting and encouraging respect for human rights and for fundamental freedoms for all without distinction as to race, sex, language, or religion.”Footnote ⁷⁰ The drafters of the Charter believed that these “conditions of stability and well-being” within states were an essential prerequisite for “peaceful and friendly relations among nations based on the principle of equal rights and self-determination of peoples.”Footnote ⁷¹ States are primarily responsible under the Charter for ensuring that their people enjoy the full protection of international human rights within their respective jurisdictions. Under Articles 55 and 56, however, they also “pledge themselves to take joint … action in co-operation with the [United Nations]”Footnote ⁷² to guarantee “universal respect for, and observance of, human rights and fundamental freedoms for all.”Footnote ⁷³ Thus, just as states must cooperate with the Security Council’s efforts to maintain international peace and security, the Charter also requires states to cooperate with one another and the United Nations to protect and fulfill human rights worldwide.

Early in the United Nations’ history, states worked through the General Assembly and the UN Economic and Social Council (ECOSOC) to specify international human rights norms in landmark agreements, such as the Universal Declaration of Human Rights,Footnote ⁷⁴ the International Covenant on Civil and Political Rights,Footnote ⁷⁵ and the International Covenant on Economic, Social and Cultural Rights (ICESCR).Footnote ⁷⁶ Over the past several decades, however, the United Nations’ focus generally has shifted from norm-specification and legal codification to securing compliance with established human rights obligations. Protecting human rights has become a core purpose of UN peacekeeping.Footnote ⁷⁷ The Security Council has exercised its Chapter VII authority with increasing regularity to mandate collective enforcement measures (e.g., economic sanctions, travel restrictions, military action) and to prevent and suppress serious breaches of international human rights norms (e.g., crimes against humanity and war crimes).Footnote ⁷⁸ Along the way, the international community has accepted that all states must cooperate when the Security Council decides that international cooperation is necessary to advance universal respect for international human rights.Footnote ⁷⁹

One of the ways states have pledged to promote respect for international human rights is by cooperating with one another and with international tribunals to facilitate the prosecution of those who commit international crimes. During the 1990s, the UN Security Council established ad hoc criminal tribunals to investigate and prosecute mass atrocities in Rwanda and the former Yugoslavia.Footnote ⁸⁰ In both settings, the Security Council issued binding regulations requiring states to cooperate with the tribunals, including by complying with requests for assistance with pretrial investigation and prosecution.Footnote ⁸¹ States later incorporated duties of cooperation into the Rome Statute of the International Criminal Court (ICC).Footnote ⁸² The Rome Statute requires states-parties to “cooperate fully with the Court in its investigation and prosecution of crimes within the jurisdiction of the Court,”Footnote ⁸³ including by gathering evidence, securing witnesses for trial, and arresting and surrendering suspects upon the Court’s request.Footnote ⁸⁴ Mandatory cooperation also features prominently in the Convention Against Torture and Other Cruel, Inhuman, or Degrading Treatment or Punishment.Footnote ⁸⁵ States-parties must not only prevent, criminalize, and prosecute domestic acts of tortureFootnote ⁸⁶ but also grant reasonable extradition requests and “afford one another the greatest measure of assistance in connection with criminal proceedings brought” to enforce the Convention, including by providing “all evidence at their disposal necessary for the proceedings.”Footnote ⁸⁷ Similar duties of international cooperation appear in the International Convention for the Protection of All Persons from Enforced DisappearanceFootnote ⁸⁸ and the Convention on the Prevention and Punishment of the Crime of Genocide (Genocide Convention).Footnote ⁸⁹

The Bosnian Genocide Case

On July 11, 1995, at the height of the violence unleashed by Yugoslavia’s dissolution, Bosnian Serbs under the command of General Radko Mladić captured the weakly fortified town of Srebrenica on the eastern fringe of present-day Bosnia and Herzegovina. Stationed at Srebrenica was a small contingent of Dutch peacekeepers operating under UN mandate but without authorization to use force for the town’s defense. Two years earlier, the Security Council had adopted a resolution designating “Srebrenica and its surroundings as a safe area which should be free from any armed attack or any other hostile act.”Footnote ⁹⁰ As Mladić entered town, however, he looked directly into a journalist’s video camera and declared, “We give this town to the Serb nation as a gift. The time has come to take revenge on the Muslims.”Footnote ⁹¹ Over the next five days, Mladić’s troops systematically rounded up and executed over 7,000 unarmed Muslim men of all ages.Footnote ⁹²

Even before the massacre at Srebrenica, Bosnia and Herzegovina had instituted proceedings in the ICJ, claiming that Serbia was legally responsible for atrocities committed on Bosnian soil by Bosnian Serb separatists.Footnote ⁹³ These proceedings gained even greater urgency after the much-publicized Srebrenica massacre. Bosnia and Herzegovina argued that Serbia violated the Genocide Convention by failing to prevent acts of genocide by Bosnian Serbs and declining to arrest and surrender General Mladić for prosecution in the International Criminal Tribunal for the Former Yugoslavia (ICTY).Footnote ⁹⁴ These legal claims raised important questions about the scope of mandatory cooperation as applied to mass atrocities. Did Serbia indeed have an affirmative obligation to prevent the Srebrenica genocide and punish those responsible? Should it make a difference that the genocidal acts were committed by foreign nationals (Bosnian Serbs) outside Serbian territory?

In its landmark judgment of February 26, 2007, the ICJ agreed that Serbia violated the Genocide Convention by failing to cooperate fully with international efforts to prevent the massacre at Srebrenica and punish Mladić.Footnote ⁹⁵ Although the Court found insufficient evidence to attribute the Srebrenica genocide to Serbia,Footnote ⁹⁶ it underscored Serbia’s affirmative obligation to prevent and punish genocide:

The ICJ acknowledged that a state’s legal responsibility to prevent others from committing genocide varies depending upon its “capacity to influence effectively the action of persons likely to commit or already committing, genocide,” as well as “its particular legal position vis-à-vis the situations and persons facing the danger, or the reality, of genocide.” However, the fact that a state might not be able to prevent genocide through its efforts alone would not suffice to excuse a failure to act. Instead, the proper inquiry was whether “the combined efforts of several States, each complying with its obligation to prevent, might have achieved the result – averting the commission of genocide – which the efforts of only one State were insufficient to produce.”Footnote ⁹⁸ Put simply, when a state cannot prevent genocide unilaterally, it must pursue international cooperation.Footnote ⁹⁹ In the case of Srebrenica, the ICJ concluded that Serbia violated its obligations under the Genocide Convention by failing to devote “the best efforts within [its] power to try and prevent the tragic events then taking shape.”Footnote ¹⁰⁰

This was not Serbia’s only violation of international law. The ICJ also concluded that Serbia “failed in its duty to co-operate with the ICTY.”Footnote ¹⁰¹ According to the Court, states-parties to the Genocide Convention must “arrest persons accused of genocide who are in their territory – even if the crime of which they are accused was committed outside it – and, failing prosecution of them in the parties’ own courts,” they must “hand them over for trial by the competent international tribunal.”Footnote ¹⁰² The Court found “plentiful, and mutually corroborative, information suggesting that General Mladić, indicted by the ICTY for genocide,” had been living freely in Serbian territory with the knowledge of Serbia’s intelligence service but without Serbia taking reasonable steps to make an arrest.Footnote ¹⁰³ This failure to cooperate fully with the ICTY violated Serbia’s duties “as a member of the United Nations” and “under Article VI of the Genocide Convention.”Footnote ¹⁰⁴

Cooperating to Prevent and Punish Other Atrocity Crimes

The Bosnian Genocide Case confirms that states bear due diligence obligations to prevent and suppress genocide and that they must cooperate with one another and with international organizations to make those efforts effective. The judgment does not directly address whether states must unite to prevent and suppress other international crimes. Still, there are strong signals elsewhere in the ICJ’s jurisprudence that all such crimes trigger mandatory cooperation. For example, in the Reservations to the Genocide Convention Case (Reservations Case), the Court explained that mandatory cooperation is a “consequence” of the Genocide Convention’s “conception” of genocide as an international crime which “shocks the conscience of mankind and results in great losses to humanity, and which is contrary to moral law and to the spirit and aims of the United Nations.”Footnote ¹⁰⁵ Based on this logic, it would seem to follow that states must cooperate to prevent, suppress, and punish other mass atrocities, as well. Genocide is not the only universally recognized international crime that shocks the conscience, generates great losses to humanity, and violates the spirit and aims of the United Nations; the crime of aggression, crimes against humanity, and at least some war crimes clearly satisfy these criteria.Footnote ¹⁰⁶ The ICJ’s reasoning in the Reservations Case suggests, therefore, that those other international crimes also trigger an obligation to cooperate in good faith “to liberate mankind from such an odious scourge.”Footnote ¹⁰⁷

Consistent with the Reservations Case, customary international law may be in the process of establishing positive duties of cooperation for grave breaches of international human rights and international criminal law. In its influential 2001 Articles on State Responsibility for Internationally Wrongful Acts (the Articles), the UN International Law Commission (ILC) concluded that under international law, states must “cooperate to bring to an end through lawful means any serious breach” “of an obligation arising under a peremptory norm of general international law.”Footnote ¹⁰⁸ The ILC’s commentary accompanying the Articles acknowledges that reasonable minds might question whether “[customary] international law at present prescribes a positive duty of cooperation,” and it concedes that the Articles’ articulation of this duty “may reflect the progressive development of international law.”Footnote ¹⁰⁹ Nonetheless, the ILC’s commentary observes that “in fact such cooperation, especially in the framework of international organizations, is carried out already in response to the gravest breaches of international law.”Footnote ¹¹⁰

Since the ILC finalized the Articles, the idea that states must cooperate to prevent mass atrocities has received some additional support from the UN General Assembly. In the 2005 World Summit Outcome, 191 states unanimously endorsed the “Responsibility to Protect” (R2P) doctrine, affirming that states are responsible for protecting their people from genocide, war crimes, ethnic cleansing, and crimes against humanity, and that “[t]he international community, through the United Nations, also has the responsibility to use appropriate … means” – including “collective action … through the Security Council” – to protect vulnerable populations from these threats.Footnote ¹¹¹ A year after the 2005 World Summit Outcome, the General Assembly clarified further that “[i]n cases of gross violations of international human rights law and serious violations of international humanitarian law constituting crimes under international law, … States should, in accordance with international law, cooperate with one another and assist international judicial organs competent in the investigation and prosecution of these violations.”Footnote ¹¹² At a minimum, these General Assembly resolutions express a shared political commitment to cooperate to prevent and punish international crimes.

Whether states accept the idea that they have a legal obligation to cooperate to prevent and suppress atrocity crimes is less clear. In practice, bystander states rarely treat international cooperation as a legal requirement absent a binding Security Council resolution. The international community’s flagrant failures to prevent genocide and crimes against humanity in Cambodia, Rwanda, Bosnia, Darfur, Syria, Myanmar, and elsewhere are well documented.Footnote ¹¹³ As these crises have unfolded, many states have turned a blind eye to imminent catastrophe. Security Council members have opposed or slow-rolled proposals to protect vulnerable populations. Reflecting on these tragedies in a 2016 Report titled Mobilizing Collective Action: The Next Decade of the Responsibility to Protect, UN Secretary-General Ban Ki-Moon lamented that “although Member States have repeatedly emphasized their support for the prevention of atrocity crimes, this has not been sufficiently translated into concrete support for preventive strategies – even when there have been credible assessments of imminent threats to populations.”Footnote ¹¹⁴ Experience thus reveals a wide gap between international institutions’ strong affirmations of mandatory cooperation to prevent and punish atrocity crimes, on the one hand, and tepid state practice, on the other hand.

The genocide in Sudan’s Darfur region (2003–2005) illustrates this challenge. In October 2003 – at least three months before international news media began reporting ethnic cleansing by Janjaweed militia in Darfur, and a full eleven months before Western governments officially labeled the attacks “genocide” – the US State Department was aware that escalating ethnic violence in the region could soon cause death rates to spike into the hundreds of thousands. The European Commission also tracked developments in Darfur closely and anticipated imminent calamity. Nonetheless, early warnings about the approaching genocide were “swept under the carpet” based on “a conscious decision to address Darfur silently using quiet diplomacy and not bring it to the UN Security Council.”Footnote ¹¹⁵ Had the European Commission and the United States recognized that the looming crisis triggered mandatory cooperation – including a firm due diligence obligation to notify the entire international community of the approaching calamity and seek timely action from the Security Council – this might have helped to avert or contain the atrocities that followed. Attending to the requirements of mandatory cooperation might have helped to persuade Security Council members, as “trustees of the international community,” to act more decisively to condemn, prevent, and suppress mass murder in Darfur.Footnote ¹¹⁶

Or perhaps not. Even when requirements of mandatory cooperation are well recognized and uncontroversial, states are not always eager to comply with their obligations. For example, in March 2009, the ICC issued a warrant for the arrest of Sudanese President Omar al-Bashir for his role in the Darfur genocide.Footnote ¹¹⁷ Under the Rome Statute and the Genocide Convention, all states-parties are obligated to cooperate in bringing al-Bashir to justice. Nonetheless, in the years that followed, over twenty countries welcomed visits from al-Bashir without executing his arrest, including China, Egypt, Ethiopia, Indonesia, Iran, Kenya, Russia, Saudi Arabia, the United Arab Emirates, and South Africa.Footnote ¹¹⁸ Although Sudan has pledged to deliver al-Bashir to the ICC for trial,Footnote ¹¹⁹ thus far it has not followed through on this commitment. The ICC has referred instances of state noncooperation to the Security Council, but its requests have been brushed aside. These failures of cooperation suggest that some states lack the political will to prioritize punishing atrocity crimes.

Cooperating for Economic, Social, and Cultural Rights

Economic, social, and cultural rights also trigger mandatory cooperation under international human rights law. The ICESCR enshrines a wide variety of rights, such as the right to work and the right to “an adequate standard of living … , including adequate food, clothing and housing, and to the continuous improvement of living conditions.”Footnote ¹²⁰ Article 2(1) declares that these rights are subject to mandatory cooperation: “Each State Party to the present Covenant undertakes to take steps, individually and through international assistance and co-operation, especially economic and technical, to the maximum of its available resources, with a view to achieving progressively the full realization of the rights recognized in the present Covenant by all appropriate means, including particularly the adoption of legislative measures.”Footnote ¹²¹ In addressing the right to an adequate standard of living, the Convention provides that international assistance and cooperation could improve methods of food production, conservation, and dissemination; disseminate agricultural techniques and best practices; and “ensure an equitable distribution of world supplies in relation to need.”Footnote ¹²² States-parties “agree that international action for the achievement of the rights recognized in the … Covenant includes such methods as the conclusion of conventions, the adoption of recommendations, the furnishing of technical assistance and the holding of regional meetings and technical meetings for the purpose of consultation and study organized in conjunction with the Governments concerned.”Footnote ¹²³

Some states have characterized these features of the ICESCR as mere political commitments, not legal obligations.Footnote ¹²⁴ However, the Committee on Economic, Social and Cultural Rights has affirmed that the Covenant’s requirements for international cooperation are legally binding. In its General Comment No. 3, the Committee has stated

This is so, the Committee observes, because “in the absence of an active programme of international assistance and cooperation on the part of all those States that are in a position to undertake one, the full realization of economic, social and cultural rights will remain an unfulfilled aspiration in many countries.”Footnote ¹²⁶ In other words, mandatory cooperation is essential to achieve the ICESCR’s object and purpose.

The Committee on the Rights of the Child has reached the same conclusion for economic, social, and cultural rights enshrined in the UN Convention on the Rights of the Child (UNCRC).Footnote ¹²⁷ Article 4 of the UNCRC requires states-parties to “undertake all appropriate legislative, administrative, and other measures for the implementation of the rights recognized in the present Convention. With regard to economic, social and cultural rights, States Parties shall undertake such measures to the maximum extent of their available resources and, where needed, within the framework of international co-operation.”Footnote ¹²⁸ “When States ratify the Convention,” the Committee explains, “they take upon themselves obligations not only to implement it within their jurisdiction but also to contribute, through international cooperation, to global implementation.”Footnote ¹²⁹

In 2011, a group of forty eminent international law experts from around the world gathered in the Netherlands to “clarify [the] extraterritorial obligations of States on the basis of standing international law.”Footnote ¹³⁰ The resulting Maastricht Principles on the Extraterritorial Obligations of States in the Area of Economic, Social and Cultural Rights (Maastricht Principles) confirms that states must cooperate in good faith to protect and fulfill economic, social, and cultural rights for those both inside and outside their territories.Footnote ¹³¹ Consistent with general principles of mandatory cooperation, the Maastricht Principles indicate that states’ cooperative obligations must be ascertained based on equitable principles, accounting for factors such as states’ respective “economic, technical and technological capacities, available resources, and influence in international decision-making processes.”Footnote ¹³² Mandatory cooperation thus gives states common but differentiated responsibilities to protect and fulfill economic, social, and cultural rights.

Mandatory Cooperation in the Real World

In the closing days of the San Francisco Conference, when negotiations over the draft Charter teetered on the brink of collapse, Truman dispatched an envoy to Moscow with instructions to “make it clear to Uncle Joe Stalin that I knew what I wanted – and that I intended to get [from the United Nations] – peace for the world for at least 90 years.”Footnote ¹³³

If perpetual peace is the standard by which the United Nations must be judged, then surely it will be found wanting. Mandatory cooperation has not saved succeeding generations from the scourge of war. Less than two months after the San Francisco Conference, Truman shocked the world by authorizing the use of nuclear weapons against Hiroshima and Nagasaki. Since World War II and the Korean War, the world has endured hundreds of devastating conflicts, including the Algerian War, the Vietnam War, the Iran-Iraq War, the Bosnian War, the Iraq War, recurring armed struggles in Afghanistan and Congo, and civil wars in Burundi, El Salvador, Guatemala, Libya, Nigeria, Sri Lanka, Somalia, Sudan, Syria, and Yemen, to name just a few. Nor has international cooperation solved the puzzle of mass atrocities. As this volume goes to print, diplomats continue to wring their hands in futility as North Korea systematically murders, rapes, and tortures detainees in prison camps;Footnote ¹³⁴ Israel continues to restrict the delivery of humanitarian aid to starving Palestinians in defiance of provisional measures indicated by the ICJ;Footnote ¹³⁵ and Russia refuses to comply with an ICC warrant to arrest Putin for war crimes.Footnote ¹³⁶ Sadly, states sometimes conspire with one another to defeat international efforts to suppress aggression and human rights abuse – including through their abuse of the P5 veto power.Footnote ¹³⁷ As long as states decline to condemn wars of territorial conquest, such as Russia’s invasion of Ukraine,Footnote ¹³⁸ it is plain that we are nowhere near the future Tennyson foresaw in which “the war-drum throbb’d no longer” and “the kindly earth shall slumber, lapt in universal law.”Footnote ¹³⁹

Still, as hard as it may be to achieve, cooperation is necessary if the international community hopes to secure sovereign equality, maintain international peace and security, and safeguard humanity from oppression. This is why the Charter enshrines mandatory cooperation as a cornerstone principle – arguably the cornerstone principle – of our international legal order.

And there is some basis for cautious (if limited) optimism. For all their shortcomings, UN peacekeeping missions have made valuable contributions to curtailing armed conflicts, reducing civilian casualties, and strengthening peace agreements, thereby saving countless lives.Footnote ¹⁴⁰ Dozens of the worst human rights abusers have been prosecuted successfully for atrocity crimes, including Mladić, who, with Serbia’s assistance, was finally tried and sentenced to life in prison for genocide by the ICTY in 2017.Footnote ¹⁴¹ Mandatory cooperation has also advanced economic, social, and cultural rights worldwide. Since 1990, international cooperation of the kind envisioned in the ICESCR has lifted more than 1.1 billion people out of extreme poverty.Footnote ¹⁴² Over fifty million lives have been saved through international cooperation to combat HIV, tuberculosis, and malaria in low- and middle-income countries.Footnote ¹⁴³ If there is a path toward a more decent and peaceful world, it runs through mandatory cooperation.