• A. The Missing Constitutional Foundations of Environmental Law

• B. The Public Trust as an Emerging Foundation for Environmental Governance

• C. The Turning Point: Mono Lake and Beyond

• D. Public Trust Principles and Environmental Rights

• E. A Brief Synopsis of What Follows

This book explores the development of one of our oldest legal principles – the public trust doctrine – which comes down to the commonsense idea that some natural resources are so important to everyone that they cannot belong to just anyone, and so the government must therefore protect them for the benefit of all the people (who, in turn, can hold the government to account). The core public trust principle that flows from this idea partners an express government obligation to protect trust resources with an implied public right to the benefit of trust resources – and after the Mono Lake case, an implied environmental right. Centering on the birth of the modern doctrine at Mono Lake, the book examines how public trust principles have come to fill an important gap in environmental law – and perhaps even constitutional law – both in the United States and around the world.

Today, public trust principles in different legal settings create public rights and responsibilities with regard to designated natural resource commons, obligating the state to manage them in trust for the public. The original common law doctrine is thought to be among the oldest of the common law, with roots extending as far back as ancient Rome and early Britain, where it primarily protected public fishing and transportation values associated with navigable waterways.Footnote ¹ Early on, the common law came to recognize that some natural resources – especially waterways – are so foundational to civilization that they cannot be owned by anyone in particular; instead, they must belong to everyone together. To prevent private expropriation or monopolization of these critical public commons, the sovereign – be it the Emperor, the King, or later, the elected legislative and executive branches of government – is entrusted to manage them on behalf of the public.Footnote ²

Over these hundreds and even thousands of years, the doctrine has gradually transformed from an affirmation of sovereign authority over trust resources to a recognition of sovereign responsibility to protect them for present and future generations – historically to ensure public access, but increasingly for environmental reasons as well. Especially in recent decades, it has evolved substantially through U.S. common, constitutional, and statutory law to address a broader variety of natural resources, from waterways to wildlife, and a broader scope of public values associated with them, including ecological, recreational, scientific, and scenic values.Footnote ³ In many jurisdictions, the doctrine operates in constitutive terms – either as a quasi-constitutional or overtly constitutionalized constraint on sovereign authority that binds governmental discretion with regard to trust resources. In others, the doctrine remains a more fluid feature of common or statutory law, deployed in different circumstances for different legal purposes. In each of these contexts, the unifying public trust principle is the sovereign obligation to protect designated public natural resources, for the benefit of citizens who are entitled to hold the state to account.

As its primary example, the book shares the epic tale of the fall and rise of Mono Lake – the strange and beautiful Dead Sea of California – which fostered some of the most important environmental law developments of the last century,Footnote ⁴ and which has become a platform for some of the most potentially important developments in the new century.Footnote ⁵ One of the all-time great stories of American environmental law, the Mono Lake epic recounts the protracted conflict over water between the City of Los Angeles and advocates for the Mono Basin, the eastern watershed of the high Sierra Nevada crest at Yosemite National Park, four hundred miles to the north. In 1983, in National Audubon Society v. Superior Court, the California Supreme Court took the first steps toward resolving that conflict by casting the public trust doctrine as an inalterable source of state obligation to protect the environmental values at stake in Mono Lake, in addition to such traditional trust values as public navigation.Footnote ⁶

The Mono Lake conflict followed a century of California’s efforts to cope with limited water resources in the face of compelling but conflicting demands, culminating in a historic legal decision that continues to influence related environmental dilemmas worldwide. The book explores the vivid backstory, unlikely journey, and lasting legacy of the California Supreme Court’s famous decision in National Audubon Society – “the Mono Lake case” – which inspired a quiet revolution in public trust ideals that has expanded to other states and even nations as far distant as India.Footnote ⁷ Even today, in the fifth decade following the decision, the case remains the leading example of environmental public trust litigation in the United States, inspiring a new age of public trust advocacy that has extended well beyond navigable waterways to groundwater, wildlife, ecosystems, and even the global climate.

Yet the modern public trust is not limited to litigation. While environmental plaintiffs still apply the doctrine against the state as a sword in litigation, and states increasingly use the doctrine as a shield in litigation to defend their actions protecting trust resources, public trust principles are also implemented at all levels of government as a guiding principle and best management practice. Whether adopted constitutionally, by statute, or in administrative regulations, public trust principles help state actors methodically consider proposed actions before they are taken to ensure that they will not inadvertently or inappropriately harm jurisdictional trust resources.

Although public trust principles appear in legal systems across the world, they remain especially important in the United States, in part because they help fill a gap in the underlying principles supporting American environmental law. The United States was an early mover toward the modern norm of constitutional governance, but it is a relative latecomer to the importance of environmental governance. And while it has helped lead the development of environmental law through such groundbreaking statutes as the National Environmental Policy Act,Footnote ⁸ the Clean Air and Water Acts,Footnote ⁹ and the Endangered Species Act,Footnote ¹⁰ even these pioneering pieces of legislation have been challenged, both directly and through their implementing regulations, in ways that reflect their more attenuated constitutional grounding in comparison to alternative constitutional frameworks.Footnote ¹¹ This attenuated support for U.S. environmental law reflects the contrasting governance concerns that prevailed at the time the Constitution was drafted. Its framers, mired in political contest over the nature of the unfolding American experiment, perceived the undue exercise of sovereign authority as the greatest potential threat, rather than the loss of environmental values in nature that perhaps only sovereign authority can protect.

Commencing the journey, this introductory chapter traces how the public trust doctrine has developed, in part, to buttress inherent weaknesses in the foundations of U.S. environmental law, providing additional support for environmental governance. It introduces the core public trust principle as a partnership between reciprocal principles of sovereign obligations and environmental rights, and how the Mono Lake case became an important inflection point in the development of the modern doctrine as a tool of environmental advocacy. It touches on the hopes and fears that ongoing doctrinal developments have engendered in proponents and skeptics, including an emerging generational divide between younger environmental advocates enthusiastic about its promise and older advocates leery of its potential to destabilize existing regulatory frameworks. It closes with a synopsis of the ten chapters that follow, fleshing out the full public trust saga in all the vivid detail it deserves.

A. The Missing Constitutional Foundations of Environmental Law

The American experiment of constitutional governance began with trial and error, but it set the global standard. In 1789, after a failed first try with the Articles of Confederation,Footnote ¹² the framers of the American Constitution outlined a tripartite structure of government that diffused sovereign power among separately acting branches and guaranteed citizens a set of inalienable rights.Footnote ¹³ Enshrined in the Constitution’s Bill of Rights, these famously included legal guarantees for freedom of speech and assembly,Footnote ¹⁴ and rights against cruel and unusual punishment.Footnote ¹⁵ But in the late eighteenth century, when open space was still plentiful, natural resources were bountiful, and the Industrial Revolution had not yet fully taken hold, environmental conflicts were not among the governance problems that worried the framers.Footnote ¹⁶ They were much more worried about the resurrection of a monarchy, and the potential for unchecked power to corrupt future leaders.Footnote ¹⁷

The oldest written constitution still in force, the U.S. Constitution remains a landmark legal accomplishment, a bedrock for the distinctive American civilization that has followed, and inspiration for many of the most important developments in democratic governance worldwide.Footnote ¹⁸ Though it remains a work in progress,Footnote ¹⁹ it is an enduring source of American identity, culture, and aspiration that forever changed the world. Even so, it stands apart today for failing to definitively address the need for environmental regulation that many of the modern constitutions it helped inspire now do as a matter of course.Footnote ²⁰

The American Constitution pioneered individual rights and enumerated sovereign responsibilities, but no part speaks directly to the responsibility of environmental stewardship, or the various rights and duties that stewardship implies. While it sets forth the basic structure and functions of government, it elides the critical role government must play in protecting not only the human rights and relationships catalogued in its articles and amendments, but also the human relationship with the shared natural resources on which we all depend for life and livelihood.

Indeed, Americans are often surprised to learn that the most solid legal basis for our primary federal environmental laws – the Clean Air and Water Acts, the Endangered Species Act, and others curtailing pollution and harms to natural resources – are based not on any kind of constitutional environmental principle but instead on the Constitution’s Commerce Clause, which empowers Congress to regulate market transactions across state, tribal, and international lines.Footnote ²¹ Since the modern environmental movement took form in the 1970s, opponents have challenged a number of these laws in court, sometimes successfully, for allegedly exceeding constitutional bounds.Footnote ²² Some of these challenges have attacked legislation directly and some have focused on their implementing regulations, often suggesting that environmental regulations exceed both statutory and constitutional authority.Footnote ²³ In other cases, the Supreme Court has overturned environmental regulations it has concluded stray so close to the boundaries of constitutionally permissible authority that clearer congressional authorization is required.Footnote ²⁴ Perhaps, the most successful federal environmental laws are those that create procedural rights and obligations,Footnote ²⁵ such as the National Environmental Policy Act, requiring government actors to “look before they leap” on taking actions that could cause environmental harm,Footnote ²⁶ and which follow from much clearer constitutional procedural traditions such as due process.Footnote ²⁷ Laws that promise substantive environmental protection require more work to ground, at least federally.Footnote ²⁸

Other nations have taken a different approach. The Swiss Constitution, for example, explicitly authorizes legislation for “the protection of the population and its natural environment against damage or nuisance,”Footnote ²⁹ removing some of the pragmatic hurdles that environmental governance has faced in the United States. The constitution of Nepal declares that “the State shall pursue … policies” that “protect, promote, and make environmentally friendly and sustainable use of natural resources.”Footnote ³⁰ In a less utilitarian commitment to environmental protection, Ecuador’s constitution recognizes environmental rights directly in nature, declaring that “Pacha Mama” (Mother Earth) “has the right to integral respect for its existence and for the maintenance and regeneration of its life cycles, structure, functions and evolutionary processes,” and that “[a]ll persons, communities, peoples and nations can call upon public authorities to enforce the rights of nature.”Footnote ³¹ Many nations in the developing world, generally with newer constitutions, provide explicit constitutional protection for environmental values.Footnote ³² Nations in the European Union and other developed nations with older constitutions have often interpreted their own constitutional promises of fundamental rights or due process to include protection for environmental values.Footnote ³³

Most American state constitutions are modeled after the federal constitution, but some have departed from that model in adding environmental promises, often based on public trust principles emphasizing sovereign responsibility to protect environmental values for the benefit of the public. Some include constitutional language explicitly recognizing the rights of citizens to enjoy a healthy environment and establishing state responsibility to protect them. For example, the Pennsylvania Constitution asserts that citizens “have a right to clean air, pure water, and to the preservation of the natural, scenic, historic and esthetic values of the environment,” and that “Pennsylvania’s public natural resources are the common property of all the people, including generations yet to come.”Footnote ³⁴ It goes on to guarantee that “[a]s trustee of these resources, the Commonwealth shall conserve and maintain them for the benefit of all the people.”Footnote ³⁵ In 1972, Montanans added constitutional language affirming that “the state and each person shall maintain and improve a clean and healthful environment in Montana for present and future generations.”Footnote ³⁶ New York’s constitution was amended in 2022 to promise “a right to clean air and water, and a healthful environment.”Footnote ³⁷

Even without these constitutional provisions, American states have plenary authority to protect environmental values within them. Many have used it to enact meaningful environmental laws, including environmental procedural requirements, antipollution laws, land use planning mandates, and resource conservation laws.Footnote ³⁸ Yet the natural resource commons most in need of protection – such as air, water, and biodiversity – very often defy jurisdictional boundaries, in that the benefits they confer and the harms we may cause them cross state lines.Footnote ³⁹ Regulating water or air pollution in one state does no good when the waterway runs through multiple states and air pollutants travel on the wind, and wildlife roams freely.Footnote ⁴⁰ Hazardous radioactive waste may require transport across multiple states or otherwise threaten shared resources.Footnote ⁴¹

The special challenge of environmental law is that state laws often require federal coordination to be effective, while federal laws often rely on state implementation to be effective.Footnote ⁴² Similar dynamics unfold at every scale of governance – from the municipal to the international – although as regulatory scale increases, regulatory tools become even weaker, leaving international environmental law more aspirational than operational in many instances.Footnote ⁴³ Moreover, even where they find solid legal foundation, both state and federal environmental laws struggle for efficacy in protecting public trust resources that are threatened for reasons other than pollution.Footnote ⁴⁴

For example, in the context of protecting American waterways, the closest thing to a unifying national strategy is the Clean Water Act. While it deserves enormous credit for reducing pollution into navigable waterways from many industrial and municipal pipes,Footnote ⁴⁵ it has no means to protect vulnerable waterways from other kinds of harm, such as agricultural or nonpoint-source pollution – or even human actions that threaten their continued existence, by siphoning them down to dangerously low levels.Footnote ⁴⁶ While the Clean Water Act regulates water quality, waterways across the world – like Mono Lake – are endangered by practices that threaten not just the quality but the quantity of water within them, often due to excessive water withdrawals under state laws.Footnote ⁴⁷ The assertions of the Act that come closest to protecting waterways as waterways – regulations that prevent the destruction of wetlands – have repeatedly been challenged in court, sometimes successfully, for straying too close to the boundaries of authority conferred by the Commerce Clause.Footnote ⁴⁸ Advocates defending waterways and other natural resources threatened by overuse have lamented the limits of the U.S. Constitution in failing to provide more straightforward authority for the kinds of regulations needed to protect them.Footnote ⁴⁹

U.S. legal tools for protecting the atmospheric commons have fared even worse. The Clean Air Act is the recognized national strategy for regulating boundary-crossing air pollution, but the statute does not specifically address climate change, and efforts to deploy it in service of climate governance have met with stiff legal resistance. The Supreme Court did recognize a federal obligation to regulate greenhouse gas pollution under the Act in Massachusetts v. EPA,Footnote ⁵⁰ and the Environmental Protection Agency (EPA) has interpreted parts of the statute authorizing the regulation of any air pollutant to support regulation of greenhouse gas pollution by cars and trucks.Footnote ⁵¹ However, the Court’s subsequent holding in West Virginia v. EPA clarified that more is needed from Congress before EPA may rely on some of its most powerful statutory tools to regulate large-scale greenhouse gas emissions from fossil fuel burning power plants,Footnote ⁵² in a decision fraught with anxiety about various constitutional boundaries.Footnote ⁵³ Of course, even robust climate governance at the national level cannot, on its own, solve the global problem of greenhouse gas pollution – but it would be significant, given that the United States is one of the world’s largest greenhouse gas polluters.Footnote ⁵⁴

One potential solution is to amend the national constitution to provide the missing authority for environmental governance. Yet further revealing the price paid by early constitutional movers, who couldn’t foresee this problem – and the lessons drawn by later constitutional drafters, who avoided it after the fact – the American Constitution is uniquely difficult to change.Footnote ⁵⁵ This cumbersome process has been successfully invoked only twenty-seven times since the nation’s founding, and only seven times in the last century.Footnote ⁵⁶ Even aggressive campaigns to correct provisions arguably in conflict with core democratic principles in other parts of the Constitution, including amendments that would secure equal rights for women, have failed in recent decades.Footnote ⁵⁷ Especially given the legislative paralysis of recent years, it seems unlikely that the Constitution will be amended any time soon to provide a stronger basis for environmental regulation.

Today, then, there are few uncontroversial choices for constitutionally grounding environmental rights or obligations on the scale needed to support meaningful climate governance. However, older jurisprudence suggests that there may have once been a potential home for such rights in the Privileges and Immunities clause of Article IV,Footnote ⁵⁸ which protects fundamental rights associated with citizenship,Footnote ⁵⁹ including interstate comity and nondiscrimination,Footnote ⁶⁰ the right to travel,Footnote ⁶¹ and potentially even the federal navigational servitudeFootnote ⁶² – a federal mandate to preserve the navigability of public waterways against private encroachmentFootnote ⁶³ that is conceptually related to the public trust doctrine itself. The Clause was once thought to protect a set of interests ranging from life, liberty, and property to the pursuit of commercial advantage and even access to public resources.Footnote ⁶⁴ If the Privileges and Immunities Clause was intended to protect citizens’ rights to life, liberty, and property, could it offer protection for citizen’s rights to a healthy environment and livable climate?

Dashing that hope as a matter of history, The Slaughterhouse Cases of 1873 reduced the potential importance of the Privileges and Immunities Clause to rights associated with interstate travel.Footnote ⁶⁵ Yet even that right is conceptually related to the federal navigational servitude that is an expression of the core public trust principle associated with the primary public commons that the Supreme Court has repeatedly affirmed receives protection under the common law public trust doctrine.Footnote ⁶⁶ Modern scholarship suggests that there may even be interest among sitting members of the Supreme Court in reinvigorating the Privileges and Immunities Clause as a source of substantive rights.Footnote ⁶⁷ It is thus possible that the Privileges and Immunities Clause could one day provide constitutional foundation for protecting additional rights, and perhaps even environmental rights – but there are no indications to expect that any time soon.

But what if there is already a source of underlying authority to help ground good environmental governance, not only procedurally but perhaps even substantively? A source that has been there all along, but that we are only just now rediscovering, or fully appreciating? While the public trust doctrine cannot single-handedly resolve this problem, the potential gap-filling importance of the doctrine – and the public trust principles that are an outgrowth of the original common law doctrine – is becoming increasingly evident.

B The Public Trust as an Emerging Foundation for Environmental Governance

This book explores the development of the public trust doctrine and examines its potential for conferring additional structural support for environmental governance at the state and even federal level. It is a role of the doctrine that has long been overlooked, but one that has proved increasingly important in supporting environmental values beyond the focus of the federal Commerce Clause, and the many state constitutions modeled after the federal constitution. Charging the government with inalienable responsibility to care for designated public natural resources, the original common law doctrine provides an enduring source of sovereign obligation with quasi-constitutional elements, arguably constraining sovereign activity in the same way the written elements of a constitution do.Footnote ⁶⁸

Public trust principles, passed down for millennia through multiple legal empires, have also been codified in state constitutions, statutes, and regulations.Footnote ⁶⁹ In the United States, where the common law trust is considered a doctrine of state law, it can function to supplement other environmental regulation, but as noted, for natural resources that traverse state boundaries – such as navigable waterways, migratory wildlife, and atmospheric resources – state law may prove insufficient. For that reason, environmental advocates have sought to expand recognition for public trust principles in federal common and constitutional law.Footnote ⁷⁰ Emerging movements for environmental rights, framed both as human rights and rights for nature directly, seek formal codification of related principles in constitutional and statutory contexts.Footnote ⁷¹

Yet the story begins more than two thousand years earlier, when Roman common law recognized the doctrine as guaranteeing that the air, the sea, and the shores of the sea must forever remain the common property of all the people, guaranteeing open public access and preventing the destruction or private monopolization of these critical public natural resource commons.Footnote ⁷² The Roman doctrine was incorporated into early English common law and even the Magna Carta, which not only set the stage for the development of accountable democratic governance but also guaranteed sovereign protection for public rights of access to coastal and forest resources.Footnote ⁷³ Eventually framed as a trust obligation for public benefit, the doctrine became part of American law when the early states seceded from the British Empire, borrowing their new legal codes from existing English common law.Footnote ⁷⁴ The sovereign obligation to protect trust resources was recognized by the U.S. Supreme Court in application to navigable waterways, expanding its reach from coastal waters to the tens of thousands of miles of great rivers, streams, and lakes that traverse the great continent.Footnote ⁷⁵ Waterways like the large inland salt sea draining the Yosemite high country at Mono Lake.

And there, at Mono Lake, the public trust doctrine would meet a critical inflection point, because it was in litigation over the fate of Mono Lake that the doctrine was most famously acknowledged as a quasi-constitutional sovereign obligation, a responsibility to account for environmental values that the state could not choose to ignore.Footnote ⁷⁶ It was at Mono Lake that the public trust doctrine – long invoked to protect a suite of access rights associated with navigability to which environmental values were incidentalFootnote ⁷⁷ – was fully conceptualized as an obligation of environmental stewardship. And depending on how stewardship is itself conceptualized, perhaps even a vehicle for protecting public environmental rights.Footnote ⁷⁸ In a decision that ultimately saved the lake from being drained away, the California Supreme Court held that the state could not simply ignore the environmental, scientific, scenic, and recreational values at Mono Lake when permitting water diversions that would destroy it.

Since then, the public trust doctrine has increasingly been deployed by plaintiffs, lawmakers, and citizens to protect environmental interests and resources that are otherwise underserved by American environmental (and constitutional) law, including the physical integrity of waterways, belowground aquifers, coastal resources, the atmospheric commons, and climate stability itself. Some of these efforts have proved successful,Footnote ⁷⁹ though many have failed,Footnote ⁸⁰ and the future remains uncertain.Footnote ⁸¹ There are clearly limits to what public trust advocacy can accomplish, especially in the absence of consensus over which resources are protected. Yet the intuitive force of the underlying legal command – sovereign stewardship of natural resource commons for the public – remains powerful in its simplicity.

However these legal developments unfold, the power of the public trust as a defender of public environmental values emerged into global view through the Mono Lake story – a made-for-the-movies tale of how a ragtag coalition of locals, students, scientists, and birdwatchers deployed this thousand year-old idea in a wholly new way. There, they undertook a David-vs.-Goliath bid to save the Mono Basin, a remote and mysterious ecosystem just east of Yosemite National Park, from the thirst of Los Angeles, one of the largest, richest, and thirstiest cities in the world.

C. The Turning Point: Mono Lake and Beyond

The Mono Lake dispute pitted advocates for the Mono Basin ecosystem and its local community against proponents of the continued export of Mono Basin water to millions of thirsty Californians four hundred miles to the south.Footnote ⁸² The controversy itself spanned decades, but the story leading up to the litigation stretches back more than a hundred years, adding depth and dimension to the tale that is easily missed on a casual reading of the Audubon Society decision itself.Footnote ⁸³ It is a case study on the challenges of, and possibilities for, balancing legitimate needs for public infrastructure and economic development with competing environmental values, all within systems of law that are still evolving to manage these conflicts. For the first time, the case plumbed the inexorable conflict that had long been developing between the public commons approach that underlies the public trust regulation of waterways and the privatization premise of the western prior appropriation doctrine of water allocation, which assigns perpetual rights to withdraw from a watercourse on a first-in-time basis.

Most important, the Mono Lake case demonstrates the evolution of the public trust doctrine from a justification for sovereign power over trust resources to a mandate for their protection. In this regard, the case presented the first opportunity for the highest court in the largest state in the land to consider the public trust doctrine as something more than ordinary common law. As framed by the California Supreme Court, the public trust doctrine functions as a quasi-constitutional foundation that creates sovereign obligations of stewardship – obligations that the sovereign cannot casually extinguish. It was this critical element that created the possibility, in at least some jurisdictions, that the doctrine could provide needed infill for the underlying gap of support for environmental law.

After demonstrating this doctrinal potential for protecting environmental values underserved by existing legal infrastructure, the Mono Lake decision inspired environmental advocates around the country (and eventually the world) to expand public trust protections into new legal mechanisms, and to seek trust protection for other environmental resources and values, such as biodiversity, groundwater, ecosystems, the atmosphere, climate stability, and a healthy environment more generally. Today, the doctrine is frequently invoked in environmental conflicts, sometimes by private plaintiffs to compel states to do more to protect trust resources, and increasingly by states in defense of environmental regulations protecting trust resources against private constitutional takings claims. Although it has not thus far impacted courts, a vigorous scholarly debate asserts its rightful application as a principle that constrains not only state sovereign authority, but also federal authority.Footnote ⁸⁴

Some public trust lawsuits have pushed the boundaries of previously recognized law, such as the atmospheric trust plaintiffs’ appeal to public trust principles in support of claims for meaningful climate governance.Footnote ⁸⁵ Some innovative lawsuits have experimented with ways to partner public trust principles with other fundamental rights that stand on firmer constitutional ground, at both the state and federal levels.Footnote ⁸⁶ American examples continue to provide inspiration for the adoption of public trust principles in foreign nations, even as the public trust provides a fascinating contrast for a simultaneously developing alternative premise for environmental law, the burgeoning Rights of Nature movement, which confers legal rights directly on nonhuman features of the natural environment.

Environmental theorists continue to search for sources of environmental rights on which to premise more effective environmental protection than our current governance models have been able to achieve. Yet the public trust doctrine – especially since the Mono Lake case – can itself be understood as a doctrine of public environmental rights. Somehow, it would seem, we just hadn’t noticed it before now.

D. Public Trust Principles and Environmental Rights

The public trust doctrine itself provides a basis for asserting environmental rights that could help buttress the inherent weaknesses of U.S. environmental law, especially when the trust is conceived as a constitutive element of sovereign authority.Footnote ⁸⁷ After all, the core public trust principle is really a pairing of two reciprocal, coequal elements – (1) a sovereign obligation to protect the environmental values of trust resources for the benefit of the public, and (2) the right of the public to benefit from the trust and hold the government to account for performance of its trust obligations.Footnote ⁸⁸ Yet one does not exist without the other. They are mirror images, lacking genuine legal meaning without the partnership implied between them. And while different examples of public trust advocacy may emphasize one side of the coin over the other, as elaborated in Chapter 9, both are always in operation.Footnote ⁸⁹ Even when the environmental advocacy focuses on the sovereign obligation element of the trust, it relies on the unspoken public right to invoke the sovereign obligation. Even when advocacy is premised on the environmental right, it implies the sovereign obligation to protect it.

In this regard, the public trust doctrine is, itself, a doctrine of environmental rights – perhaps even the original statement of environmental rights, at least within the western legal tradition. It stands for an ancient but evolving conception of partnered environmental rights and duties – a sovereign obligation that delimits governance, removing the government’s option to destroy or allow these public natural resources to be destroyed, and reciprocally, an entitlement of the citizenry to the benefits of this stewardship obligation.

The big question, perhaps, is what these environmental rights entail.

Framing the rights conferred by the doctrine as legal entitlements to specific environmental goods – to a clean and healthful environment, for example – poses a conceptual hurdle in the United States, where positive rights are few and far between. In contrast to the more familiar framing of individual rights as negative rights, which constrain how the government engages with citizens, positive rights empower citizens to demand something affirmative from the government. While positive rights find reference in important sources of international human rights law,Footnote ⁹⁰ American law generally regards them with suspicion. The U.S. Constitution does recognize a few positive rights, for example, the right to jury trial and legal representation in a criminal case,Footnote ⁹¹ and many U.S. states recognize a fundamental right to free public education,Footnote ⁹² but most constitutional rights are framed as negative rights that constrain how the government can behave – such as rights against unreasonable search and seizureFootnote ⁹³, cruel and unusual punishment,Footnote ⁹⁴ or undue interference with the practice of religion.Footnote ⁹⁵ Some invocation of public trust principles in support of environmental rights – for example, to climate stability – are framed as necessary for human survival,Footnote ⁹⁶ yet the U.S. Constitution does not provide a positive right to food or medicine, even though they, too, are arguably necessary for survival.

Even so, several state constitutions arguably premised on public trust principles have done exactly that – for example, Montana’s promise of “a clean and healthful environment,”Footnote ⁹⁷ or New York’s guarantee of “a right to clean air and water, and a healthful environment.”Footnote ⁹⁸ Moreover, environmental rights protected by the public trust doctrine, which poses a constraint on sovereign action, are just as naturally framed in terms of the negative rights that are commonplace in constitutional law. They constrain the government from authorizing or permitting the private expropriation of a public trust commons it holds in trust for the public. Pennsylvania overtly expresses both sides of this reciprocal coin in its constitution, which partners a guarantee that “[t]he people have a right to clean air, pure water, and to the preservation of the natural, scenic, historic, and esthetic values of the environment” with its affirmation that “Pennsylvania’s public natural resources are the common property of all the people, including generations yet to come” and a sovereign commitment “as trustee of these resources [to] conserve and maintain them for the benefit of all the people.”Footnote ⁹⁹ Yet arguably, the two models would yield similar results, even if Pennsylvania had left out the overt statement of positive rights – as do still other state constitutions, which include only the statement of sovereign obligation.Footnote ¹⁰⁰

Environmental rights skepticsFootnote ¹⁰¹ may argue that the environmental dimensions of the trust are better framed as a mandate for environmental stewardship by the government, especially given the balancing act the Mono Lake case expressly required.Footnote ¹⁰² Yet that argument raises interesting questions about the meaningful distinction between environmental rights and stewardship obligations, if rights and duties are properly understood as reciprocal functions of one another.Footnote ¹⁰³ Does a legal duty obligating one always imply a right held by another? At least one scholar has argued that human environmental rights necessarily imply a codification of public trust-themed sovereign management, arguing that “some of nature’s gifts inherently belong to all people, and the government must steward these to prevent both private arrogation of public resources and the ‘tragedy of the commons’ [that could arise] from unfettered public access to these shared resources.”Footnote ¹⁰⁴

If so, then what is the meaningful difference between environmental stewardship and environmental rights? Is a right wielded by individuals inadequate to protect future generations, as stewardship implies? But why cannot a public right encompass the interests of members both present and yet to come? Perhaps it has to do with the intersection between the environmental content of a stewardship obligation and the countervailing public interests with which it may collide. If that environmental content is framed as a right, does that imply that it will trump all other factors, including property rights, or even competing human rights? If framed instead as a stewardship obligation, does it automatically require a balancing among competing considerations in the overall calculus of the public benefit? Or would each of these conflicts arise under either frame of reference, requiring resolution on the basis of each individual case or controversy? Does it help to frame the trust as a right that belongs to the public at large, but which individuals vindicate as “private attorneys general” on behalf of the broader community?Footnote ¹⁰⁵ What, if anything, distinguishes environmental rights from other kinds of rights?

Clearly, the provocative suggestions here raise important questions about the nature of public and private rights and their relationships to broader environmental values, some of which go beyond the scope of this book. The goal here is to provide a starting point for needed discussion of these issues, and likely not a finishing point. Yet whether framed as a doctrine of environmental rights or environmental stewardship, the public trust principles increasingly found in domestic and international jurisprudence provide compelling legal tools to secure legal protections for environmental values left vulnerable under conventional antipollution laws. Especially in the United States, where constitutional support for environmental law is complicated by features of omission and attenuation, the doctrine may provide environmental advocates – especially young advocates – the tools they feel they need to fight for their own futures, and for the future of nature itself.

That said, expansive public trust advocacy has also prompted concern among other advocates that it could undermine support for conventional environmental laws that have been far more effective in such contested realms as climate governance, displacing precision regulatory oversight with aspirational goals and vague legal demands.Footnote ¹⁰⁶ Even if these reciprocal sovereign obligations and environmental rights are recognized, what exactly could their relatively vague directives deliver? Meanwhile, doctrinal opponents contend that these efforts are antidemocratic – dangerously empowering litigants over electorates and courts over legislatures, at a time when judicial power is already waxing.Footnote ¹⁰⁷ In the ongoing struggle for good environmental governance, there is rarely a dull moment.

E. A Brief Synopsis of What Follows

The Mono Lake case will turn fifty in the coming decade. After all these years, the Mono Lake story still prompts reflection about the way the public trust doctrine navigates complex conflicts between public and private rights in natural resource commons, from ancient protections for waterways to contested claims for atmospheric resources. It is a wonderful tale to tell, and as detailed in the Preface, it is also very dear to me personally – because it centers on the legal case that personally brought me into the law. During the aftermath of the California Supreme Court’s decision, I lived and worked in the Mono Basin, serving as an interpretive ranger on the Mono Lake District of the Inyo National Forest, just east of Yosemite National Park. There, it was my job to share this story with the visiting public until it eventually inspired me to leave the Forest Service for law school, and eventually, an academic career – where it is now my job, and a great personal pleasure, to share a much fuller version of that story with you.

The chapters that follow plumb the story of the public trust doctrine from ancient Rome to the present day, pausing at length on the Mono Lake story that proved its environmental turning point, before turning to the ongoing development of public trust principles in environmental governance across the nation and the world.

Chapter 1 begins by introducing the main cast of characters in the Mono Lake story, starting with the two legal doctrines around which the conflict unfolds – the public trust doctrine that protects public rights in waterways and the prior appropriations doctrine that allocates private rights to the waters within them, set on an inexorable path of conflict. It traces the arc of public trust development from the time of the Roman Empire to the British Magna Carta, through early English common law to its reception in the new American states and by the U.S. Supreme Court, establishing the legal premise that the government holds certain natural resources in trust for the benefit of the public. Chief among them, navigable waterways like Mono Lake. It more briefly introduces the doctrines by which Americans assign legal rights for groups and individuals to take water out of these public waterways for private use, setting up the inevitable legal conflict that would unfold at Mono Lake.

Chapters 2 and 3 introduce the three places at the center of the drama – Los Angeles, the Owens Valley, and the Mono Lake Basin – in recounting the history of the Californian water struggles leading up to the Mono Lake case. Chapter 2 describes the path to the Los Angeles Aqueduct, a miracle of modern engineering that was nevertheless flawed by questionable dealings with local communities to acquire the needed land and water rights to build, as well as the catastrophic failure of the early St. Francis Dam that terrorized the downstream communities. It reviews how the aqueduct has forever changed the Owens Valley before extending even further north to the Mono Basin. Chapter 3 introduces the majestic Mono Basin, its unique ecosystem, indigenous inhabitants, and western settlers, and then recounts the serious environmental harms that befell the area following the arrival of the L.A. Aqueduct (and the departure of Mono Basin water).

Chapters 4 and 5 present the most famous arc of the made-for-the-movies Mono Lake story. Chapter 4 reviews the strategic mobilization of broader communities of interest to protect the failing lake, demonstrating the effective synergy between simultaneous legal and political processes in the overall effort to save the lake. It tells the story of how a loosely organized coalition of locals, scientists, birdwatchers, scholars, and advocates forged a rural–urban partnership around this new legal idea that would change history. Chapter 5 explores the Mono Lake case itself, analyzing the arguments that made it to the California Supreme Court, the court’s disposition of them, and the significant doctrinal developments in its decision – affirming application of the doctrine to environmental values, extending its reach over expanses of watershed and time, and ensuring its durability against countervailing statutory claims.

Chapters 6 and 7 explore the aftermath of the Mono Lake case, both on the ground locally and in the wider world of legal ideas. Chapter 6 reviews the practical aftermath of the California Supreme Court’s conclusion, including the establishment of surrounding state and national parklands, a series of buttressing litigation by CalTrout and other environmental plaintiffs, the Water Board’s implementation of these judicial directives in the famous “Decision 1631,” and Los Angeles’ resulting embrace of conservation. It also updates the more recent state of affairs in both the Mono Basin and Owens River Valley.

Chapter 7 reviews the scholarly response to the Mono Lake decision, both praise and criticisms, from advocates for the environment, private property rights, and legal process. It reviews the impact of the Mono Lake doctrine on related public trust cases and executive actions in California and other states. The chapter also considers one of the most important legal issues raised by the Mono Lake case: the actual nature of the public trust as a legal doctrine. Is it a quasi-constitutional constraint limiting sovereign power to harm trust resources, overriding all but other constitutional guarantees? Or is it a feature of ordinary common law, which is easily abrogated by statute, or overridden by subsequent legislative or executive priorities in the moment? It then explores the contrasting interpretive approaches taken in three western states with similar water management challenges – California, Idaho, and Nevada.

Chapters 8, 9, and 10 explore the development of the public trust doctrine more broadly, domestically and internationally. Chapter 8 reviews the development of the doctrine and related public trust principles well beyond the shores of Mono Lake, analyzing its development across the United States along five central planes: (1) the different forms of law by which public trust principles operate; (2) the different natural resources protected by the doctrine; (3) the different societal values protected by the doctrine; (4) different legal theories about the nature of the doctrine; and (5) different legal remedies made available under the doctrine. It also assesses doctrinal intersections with federal law, discussing its role as a background principle in defending against Fifth Amendment takings challenges; reviewing a secret history of negotiations among U.S. Supreme Court justices to avoid ruling on the doctrine; and addressing whether the doctrine constrains federal as well as state authority.

Chapter 9 explores the potential evolution of the doctrine in application to air and atmospheric resources – one of the resources overtly designated for protection by the original Roman statement of the trust – and how the partnered public trust principles of sovereign obligations and public environmental rights are reflected in an emerging movement of global climate advocacy. The chapter describes an ongoing series of judicial and executive actions brought by environmental advocates worldwide, relying on these twin public trust principles in efforts to hold governments accountable for policies alleged to contribute to climate change. These lawsuits, the most successful of which have incorporated simultaneous constitutional claims, center on the idea that citizens have a right to insist that the government not be complicit in permissively enabling private polluters to expropriate the atmospheric commons for use as a carbon sink. Arrestingly, most of these claims have been brought by youth plaintiffs arguing that they represent the interests of future generations. These youth have achieved global awareness and admiration, though some older environmental advocates worry that their efforts could undermine the success of more established environmental laws, while others worry that they threaten the constitutional separation of powers that undergirds democracy.

Moving fully forward from the Mono Lake case and even the American public trust, Chapter 10 reviews the proliferation of public trust principles on all inhabited continents of the world, reporting on examples from Oceania, Asia, the Greater Middle East, Africa, Europe, South America, and North America. It also considers the coevolution of environmental doctrines worldwide that take alternative approaches to public commons and stewardship, such as ancient Ottoman law and the modern Rights of Nature movement. Chapter 10 especially contrasts the use of public trust principles for environmental protection with the simultaneously unfolding rights of nature model. In asserting rights for natural systems directly, rights of nature initiatives offer a biocentric alternative to the anthropocentrism of the public trust, which locates rights in human members of the public. After a brief review of developing rights of nature initiatives across the globe and in the United States, Chapter 10 considers the surprising ways in which these two philosophically dissimilar approaches showcase pragmatic overlap.

Finally, the Conclusion closes with reflections on the open questions the Mono Lake story leaves us to ponder about the public trust doctrine, including the force and flexibility of the doctrine, whose interests count when we talk about the “public” trust, and which to account for when balancing the competing considerations in public trust conflicts. It considers the ontological nature of the doctrine itself, and how the quasi-constitutional features of the doctrine intersect with other constitutional considerations, such as the separation of powers, jurisprudential standing limitations, and the institution of citizen suits. It considers the antidemocratic critique of the doctrine, and the wisdom of entrusting the judiciary with administration of the trust when judicial power is already on the rise. Finally, it reviews a set of Mono Lake stories unfolding in other parts of the world, including the Great Salt Lake in Utah, the Israeli Sea of Galilee, the Dead Sea between Israel and Jordan, and the Aral Sea in Kazhakhstan.

These contested issues are what make the public trust doctrine so fascinating, so powerful, and so critical as we confront a future of ongoing and inevitable conflicts over natural resource values, new and old. Our different answers to these concluding questions in each of the Mono Lake stories reviewed here (and countless others) prompt us to reflect on the role of the doctrine in helping us navigate the challenges of environmental governance in general.