A RENAISSANCE OF THE DOCTRINE OF REBUS SIC STANTIBUS?

Abstract Once the ‘popular plaything of Realpolitiker’ the doctrine of rebus sic stantibus post the 1969 VCLT is often described as an objective rule by which, on grounds of equity and justice, a fundamental change of circumstances may be invoked as a ground for termination of a treaty. Yet recent practice from some States suggests that it is returning with a new livery. They point to an understanding that is premised on vital State interests––a view popular among scholars such as Erich Kaufmann at the beginning of the last century.


INTRODUCTION
'Circumstances alter cases'. Use of this famous proverb can be traced back as far as the seventeenth century writings of the English literary critic and historian Thomas Rymer. 1 Behind it lies the idea that what ought to be done in a given case may at times depend on the surrounding circumstances. Accordingly, when circumstances change a reassessment of the approach to be pursued may be justified. It is an idea that has also found expression in international law. Article 62 of the Vienna Convention on the Law of Treaties (VCLT), 2 which is considered to represent in many respects customary international law, 3 codifies a doctrine that in exceptional cases allows for the termination or invoked again. According to this theory, which is premised on the rights to selfpreservation and vital development of States, 'the changes of circumstances which must be regarded as fundamental or vital are those which imperil the existence or vital development of one of the parties'. 12 This indicates a shift from the 'shared-expectations' approach that takes the intentions of all parties to a treaty into account, to an approach that puts more emphasis on the treaty's adverse effects on a single party. 13 This phenomenon will be explored in four parts. The first part offers an overview of recent practice. The second part provides a broader historical contextualisation of the vital States' interests theory. The third part presents the stance expressed in the VCLT. Finally, the concluding remarks evaluate the significance of the recent practice and offer a tentative outlook for the future.

I. RECENT STATE PRACTICE
At first, practice on the doctrine after its codification in the VCLT was sparse. An exception was the end of the Cold War and the consequential reorganisations in many political systems in Europe and other parts of the world. This led to a political climate which induced a number of attempts to invoke the doctrine. 14 Yet already in 1997, the ICJ's decision in the Gabčikovo-Nagymaros Project case brought a provisional end to this phase. Since the treaty in question provided for a joint investment programme, the Court held that the prevalent political and economical conditions in the former socialist States, which had subsequently emerged into a market economy, were not so closely linked to the object and purpose of the treaty that they had constituted an essential basis for the consent of the parties. 15 Thus the ICJ determined whether the circumstances constituted an essential 12 Fisheries Jurisdiction (n 3) 20 [38]. 13 The term 'shared-expectations' approach is adopted from OJ Lissitzyn, 'Treaties and Changed Circumstances (Rebus Sic Stantibus)' (1967) 61(4) AJIL 895. 14  15 Gabčikovo-Nagymaros Project (n 3) 64 [104].
basis for the conclusion of the treaty (Article 62(1)(a) VCLT) by reference to the treaty's object and purpose. 16 In addition, the ICJ also interpreted the condition of whether the change of circumstances had radically transformed the obligations to be performed under the treaty (Article 62(1)(b) VCLT) by reference to the treaty purpose, when stating that:

A. Changes of Policy in the Domestic Realm
The first kind of argument which has developed is the proposition that new constitutional arrangements in the domestic legal order of the invoking State may give rise to a fundamental change of circumstances that allows for the termination of treaties under international law.
1. Poland's 1999 termination of five bilateral treaties on cultural and scientific cooperation Two years after the Gabčikovo-Nagymaros Project decision, in 1999, Poland sought to terminate five bilateral treaties on cultural and scientific cooperation 19 that had been concluded with the Union of Soviet Socialist 16 cf also Racke v Hauptzollamt Mainz (n 3) para 54, where the Court of Justice of the European Union determined whether the circumstances constituted an essential basis of the consent of the parties to be bound by the treaty in question by reference to the preamble and the article which expressly stipulated the treaty's object and purpose. 17 Gabčikovo-Nagymaros Project (n 3) 65 [104]. 18  and Mongolia can be considered to represent subsequent practice as a supplementary means of interpretation of Article 62 VCLT under Article 32 VCLT. 26 The same applies to the omissions of Laos, Russia, Ukraine and Belarus to object. 27 In the case of the treaty concluded with Cambodia, it is reasonable to assume that Poland invoked the doctrine under customary international law as reflected in the VCLT. 28 As a result, the termination of this treaty represents State practice and expresses the opinio juris of Poland and Cambodia in this respect.

Kenya's National Assembly resolution demanding withdrawal from the Rome Statute
In 2013, Kenya's National Assembly approved a resolution, urging the government to withdraw from the Rome Statute 29 as a change in the government was said to constitute a fundamental change of circumstances. 30 A similar motion was adopted in the Senate. 31 It has been argued that 'although it is unclear whether the motion's drafters invoked "fundamental changes of circumstances" deliberately, or inadvertently, such language in the motion' resonates 'with international treaty law'. 32 Concerned by these developments, the President of the Assembly of States Parties expressed the hope that Kenya would remain within the Rome Statute. But she also noted that in accordance with Article 127 of the Rome Statute a withdrawal would take effect only one year after formal notification 26 ILC, 'Conclusions on subsequent agreements and subsequent practice in relation to the interpretation of treaties, with commentaries', UN Doc A/73/10, conclusion 4(3) 27-37. 27 cf also WTO, EC -Customs Classification of Frozen Boneless Chicken Cuts--Report of the Appellate Body (12 September 2005) WT/DS269/AB/R and Corr.1, WT/DS286/AB/R and Corr.1 [272]: 'the "lack of reaction" or silence by a particular treaty party may, in the light of attendant circumstances, be understood as acceptance of the practice of other treaty parties. Such situations may occur when a party that has not engaged in a practice has become or has been made aware of the practice of other parties (for example, by means of notification or by virtue of participation in a forum where it is discussed), but does not react to it.

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International and Comparative Law Quarterly and not affect any ongoing proceedings. 33 Her remarks on the withdrawal clause stipulated in the Rome Statute suggest that she did not understand the motions to refer to the legal doctrine of fundamental change of circumstances. The International Criminal Court (ICC), however, appeared to at least consider the invocation of the doctrine possible. It requested the Kenyan government to clarify the legal implications of the legislative branch's endeavours. Thereupon, Kenya's Attorney General assured the Chamber of the government's intention 'to continue fully cooperating with Court'. He affirmed that 'should there be any material change of circumstances' the government would inform the ICC accordingly. 34 Hence, the motions have not succeeded yet in convincing the government to leave the Court. As Kenya has neither ratified the VCLT nor has it become a party to its sister convention on treaties applicable to international organisations 35 the two motions cannot be treated as practice in the application of these Conventions. Nevertheless, the motions could represent evidence of State practice on the doctrine under customary international law. The inconsistency between the motions and the Attorney General's statements, as well as the fact that the government has not acted upon the legislature's endeavours, reduces, however, the weight that can be attached to this practice. 36 But the jury is still out. In December 2016, President Uhuru Kenyatta proposed a reconsideration of the motions, as the ICC had 'become a tool of global power politics and not the justice it was built to dispense'. 37
A year later, a special committee of the National Assembly in charge of analysing the denunciation of a number BITs confirmed this view. 39 Consequently, Ecuador's National Assembly approved the termination of the BIT in 2017. 40 It should be noted, however, that when issuing the decree, the President relied primarily on the withdrawal clause in the investment treaty. 41 This was presumably because of Chile's declared adherence to what it called a 'general principle of the immutability of treaties'--with the exception of withdrawal clauses stipulated in a treaty--and its reservation to Article 62(1) and (3) VCLT. Consequently, the invocation of the doctrine would have required a more complex justification than simply exercising the right of withdrawal set out in the BIT. If Chile had objected to the invocation of the doctrine, the state of unconstitutionality would have been further prolonged. But since Chile also accepted the denunciation in accordance with the withdrawal clause stipulated in the treaty, it is questionable whether the President's decree represents State practice on Article 62 VCLT. 42 Moreover, although national courts decision may count as State practice 43 and evidence of a State's acceptance as law (opinio juris), 44 less weight can be accorded to the Constitutional Court judgment as it remains unenforced. 45 Hence the question arises whether the court decision may still be used as a subsidiary means for the determination of the doctrine under customary international law. 46 The value of Ecuador's Constitutional Court decision for this particular purpose depends primarily on its reception by other State organs. 47 In this regard, it bears mentioning that the presidential decree also referred to the Constitutional Court judgment and to the report of the Commission for Comprehensive Audit of the Reciprocal Investment Treaties and the Investment International Arbitration System in Ecuador (CAITISA), which had been made public earlier that month. The CAITISA report proposed the termination of several 39  related to the subject matter of the treaty had occurred which had jeopardised the supreme interests of the US. 52 In view of this, it decided to withdraw pursuant to Article XV(2) ABM Treaty--a decision that Russia accepted with regret, 53 whereas the Ukraine thought it to be matter between Russia and the USA. 54 As the argument in the diplomatic note mirrors the language of the termination clause and since, in accordance with this provision, the withdrawal was to take effect six months from the date of notice, it seems more convincing not to regard the termination of the ABM Treaty as practice on Article 62 VCLT. 55 Nonetheless, the existence of Article XV(2) ABM Treaty and its invocation demonstrate that when it comes to questions of national security, States still seek to reserve a right to terminate a treaty when they consider that the treaty in question impedes vital State interests.

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International and Comparative Law Quarterly 'resulting in a fundamental change in strategic stability', were claimed to constitute a fundamental change of circumstances within the meaning of the VCLT. 59 Remarkably, Russia found it necessary to stress that the plutonium covered by the PMDA would remain outside the nuclear weapons sphere. 60 It thereby indicated that the plutonium was still not required for defence purposes and that Russia did not intend to breach the agreement. The foreign ministry explained that the point was rather to make the US realise that it was no longer possible to cooperate with other countries only in the spheres that would benefit it and to take measures to inflict massive damage to its partners in the other spheres. 61 This explanation prompts the question whether Russia was not invoking changes outside the treaty, but which were stemming from other spheres. Regardless of whether or not one agrees with this description of the facts, the argument reveals an understanding of the doctrine that is linked to national security interests which need to be preserved and to damage which has to be averted by the State; in other words, the fundamental right of States to self-preservation which would be threatened, if the State party was to comply with the obligations set out in the treaty. In its immediate response the US engaged with the argument of national security interests. Although regretting Russia's decision to suspend the treaty, it disputed only the assessment of facts, but did not object to the interpretation of the doctrine when arguing that it was in each side's national interest to continue the application of the treaty. 62 It therefore appeared to have accepted that impeding national security interests could constitute a fundamental change of circumstances. Its latter assessments were more critical, however. In its 2017 and 2018 reports on 'Adherence to and Compliance With Arms Control, Nonproliferation, and Disarmament Agreements and Commitments', the Department of State asserted that while there was 'no indication the Russian Federation … violated its obligations under the PMDA', it had not 'articulated a valid basis' for the suspension. 63 Russia's foreign ministry reacted by reiterating its position that 'unilateral unfriendly actions of the United States, which have resulted in a fundamental change of circumstances compared to those existing at the time when the treaty was concluded … created a threat to strategic stability' which permitted the suspension of the treaty in accordance with Article 62 VCLT. 64 Thereafter, the USA struck a more conciliatory tone. It clarified in its 2019 report that whether its potential concern with respect to Russia's intent to comply with PMDA had a basis could 'better be determined if and when the two sides re-engage under the PMDA'. 65 As the US has not ratified the VCLT, it can be assumed that Russia's suspension represents State practice on the doctrine under customary international law. The US responses are more difficult to assess. The acknowledgement that the two parties are currently not engaging under the treaty suggests that the US has accepted the suspension of the PMDA. In this sense, it appears reasonable to regard its tacit acceptance as practice under the circumstances.

The Danish emergency brake law
Another recent example of such an approach comes from Scandinavia. Although a European Union (EU) Member State, Denmark enjoys a special position within the Dublin framework for the treatment of claims to international protection within the Union, as these regulations 66 only apply to Denmark on an intergovernmental basis. 67 On 15 March 2017, the Danish Minister for Immigration introduced a bill into Parliament, which provided for an emergency brake (nødbremse) in times of high influx of asylumseekers, according to which Denmark would not be obliged to follow the procedures of the EU's Dublin regulation. 68 The bill was justified on the basis that under general international law any treaty was subject to the condition that the circumstances had not materially changed so that the performance of the treaty obligations had become seriously detrimental to a State party. In the case of unforeseen changes, which have the effect of making the fulfilment of the treaty obligations a serious threat to a State's existence or welfare, the treaty could be terminated on the basis of general emergency principles. On that note, the Minister referred to the clausula

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International and Comparative Law Quarterly rebus sic stantibus under international law. 69 This argument is difficult to reconcile with the 'shared-expectations' approach. Despite not being applicable to Denmark, 70 it can hardly be claimed that the Kingdom was unaware of Article 64(2) of the Treaty establishing the European Community 71 --nowadays Article 78(3) TFEU 72 --which provided for measures that could be adopted in the case 'of one or more Member States being confronted with an emergency situation characterised by a sudden inflow of nationals of third countries'. Therefore, high influxes of asylumseekers cannot be considered to represent an unforeseeable event. 73 The argument corresponds better to the vital interests theory. The reference to threats to the existence and welfare of the State are explicit allusions to the fundamental rights of States to the vital development and self-preservation. Despite criticism by the United Nations Commissioner for Refugees, 74 the Danish Parliament passed the Act on 11 May 2017. 75 Although Germany-presumably the most relevant neighbouring State in this particular context-has been informed, it has so far abstained from taking a stance on the validity of the legal argument. 76 The EU has likewise refrained from expressing its legal opinion on the matter. An explanation might be that reform of the Dublin process is currently under negotiation, which is supposed to include a corrective allocation mechanism in those cases where a Member State is confronted with a disproportionate number of applications for international protection. 77 But not too much weight ought to be attached to the EU's silence. After all, the Act has not yet been applied in practice. 78 In any case, the enactment of the domestic law and the justification provided by the minister represent evidence of State practice 79 and of Denmark's opinio juris on the doctrine under customary international law. 80

II. THE VITAL INTERESTS THEORY
The full significance of the practice presented in the previous section becomes clear in the light of the broader historical context. The argument of vital State interests, with its focus on the burden placed on an individual treaty party rather than on the common intentions of all the parties to the treaty in question, is not a new phenomenon. Since its earliest days, the doctrine has often been linked to such arguments. Hugo Grotius, for example, found the doctrine to be applicable if the performance of the treaty obligations led to the ruin of the State. 81 At the end of the nineteenth century and the beginning of the twentieth century academics and practitioners refined this theory. An influential view at that time combined the concept with a theory on fundamental rights of States. These fundamental rights were considered to be the only vital interests which allowed for the termination of treaties. As a result, a State could abrogate a treaty if compliance with the obligations forced a State to sacrifice its inherent rights to vital development or self-preservation. This theory is usually attributed to the Austrian public international lawyer Georg Jellinek, 82 who described it in terms of a right of necessity in cases where the self-preservation of a State was imperilled. 83 Other renowned proponents included Erich Kaufmann, who developed his theory in his 1911 book Das Wesen des Völkerrechts und die clausula rebus sic stantibus, 84 and Lassa Oppenheim, as can be seen in the first three editions of his famous textbook International Law: A Treatise. 85 The former Solicitor of the US Department of State, 86 Lester H. Woosley, 87 and the Chinese scholar Ching-Lin Hsia 88 can also be counted amongst those who linked the doctrine to the vital development of States and the right to existence. 89 Therefore, it does not come as a surprise that in the Fisheries Jurisdictions case this understanding was presented as the traditional view: The invocation by Iceland of its 'vital interests', which were not made the subject of an express reservation to the acceptance of the jurisdictional obligation under the 1961 Exchange of Notes, must be interpreted, in the context of the assertion of changed circumstances, as an indication by Iceland of the reason why it regards as fundamental the changes which in its view have taken place in previously existing fishing techniques. This interpretation would correspond to the traditional view that the changes of circumstances which must be regarded as fundamental or vital are those which imperil the existence or vital development of one of the parties. 90 The danger of the vital interests theory becomes apparent, however, when taking Hersch Lauterpacht's observations into account. In The Function of Law in the International Community, he found that 'on those rare occasions on which treaties were broken under colour of the doctrine rebus sic stantibus it was obvious that no question of self-preservation arose unless, indeed, every change in the constellation of power enabling the State to disregard with impunity an onerous obligation be regarded as a material change of conditions implied in the treaty'. 91 What this statement demonstrates is twofold. On the one hand, the vital interests theory, although formulating a limit to the binding force of treaties, had the side effect of constraining the doctrine by stipulating a high threshold that had barely been met in practice. As James Brierly pointed out, 'an unforeseen change of such magnitude as to imperil the existence of one of the parties is so rare as to be negligible'. 92 But on the other hand, as long as States were not inhibited from determining on a subjective basis what exactly their vital interests were, the theory posed the risk of abusive assessments on part of the invoking States. 93 From a doctrinal perspective then, the invocation of subjectively determined vital interests in connection with the doctrine asserted 'that the rule pacta sunt servanda does not apply to States with the same cogency as it applies to individuals, for the simple reason that they are States, and that their interests cannot be subjected to an obligation existing independent of their own will'. 94 As a consequence, the binding character of international treaties could be negated in the domain of vital interests. 95

III. THE APPROACH OF THE VCLT
Back in 1944, Brierly thought this self-judging character of the vital interests theory had its roots 'in the insecurity of the existing order, in the fact that every state has hitherto had to make its own defence the prime consideration of all its policies'. But 'if a world security order in which states had confidence could be established, . . . the most difficult kind of vital interests would begin to lose their urgency'. 96 Hence the sophisticated collective security system established in the UN Charter system of international law after World War II provided an opportunity to reassess the cogency of the vital interests theory--an opportunity which was embraced with the conclusion of the VCLT.

A. Changes of Policy in the Domestic Realm
In his second report on the law of treaties, Special Rapporteur Sir Humphrey Waldock proposed inserting a paragraph stipulating that a change in the policies of the State seeking to terminate a treaty, or in its motives or attitude with respect to a treaty, could not constitute a fundamental change of circumstances. 97 Other members of the ILC, however, 'while not dissenting from the view that mere changes of policy on the part of a government cannot normally be invoked as bringing the principle into operation, felt that it would be going too far to state that a change of policy could never in any circumstances be invoked as a ground for terminating a treaty' and 'instanced a treaty of alliance as a possible case where a radical change of political alignment by the government of a country might make it unacceptable, from the point of view of both parties, to continue with the treaty'. 98 As a result, Article 62 VCLT does not contain a paragraph excluding explicitly the invocation of changes of policy.
Nevertheless, the ILC recognise the dangers of abusive attempts to terminate treaties on the basis merely of a change of policy. 99 The example of treaties of alliances, the majority adduced, suggests that in those exceptional cases where a change of policy is considered to be sufficient, the change must be accepted by all parties to the treaty. 100 In addition, the change must not be caused by the party invoking the doctrine. It may not be invoked as a ground for terminating a treaty, if it is the result of a breach by the invoking State of obligations owed to the other party (Article 62(2)(b) VCLT). These obligations include the performance of the 96

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International and Comparative Law Quarterly treaty in good faith (Article 26 VCLT). 101 Moreover, the doctrine cannot be interpreted in a way that conflicts with the principle of State continuity and so a change of government, or even in the system of government, will usually not qualify as a fundamental change of circumstances. 102 In this vein, Australia expressed the view during the negotiations of the VCLT that if 'a change of political attitude made the treaty unacceptable to both parties, they should obviously agree to terminate it', but 'a change in government policy should in no event be invoked as a ground for unilaterally terminating a treaty.' 103

B. Vital State Interests
When explaining the rationale behind the doctrine, the ILC acknowledged that as a result of a fundamental change of circumstances the provisions of a treaty might come to place an undue burden on one of the parties. If international law was not to offer any legal means for terminating the treaty then this could impose a serious strain on the relations between the States concerned, which might ultimately impel States to take action outside the law. 104 This 'undue burden' approach--which can be seen as a less radical version of the vital interests theory--has found expression in the requirement that the effect of the change must be to radically transform the scope of obligations still to be performed under the treaty. 105 But this requirement is not a sufficient criterion on its own. It constitutes just one of the five requirements of Article 62 VCLT. The change must also be (1) of circumstances existing at the time of the conclusion of the treaty, (2) fundamental, (3) not foreseen by the parties and (4) the existence of those circumstances must have constituted an essential basis of the consent of the parties to be bound by the treaty. The reference to the essential basis of the consent of the parties demonstrates that the ILC dismissed any theory that linked the doctrine to any general changes quite outside the treaty. 106 What is more, the ILC decided not to use the term 'rebus sic stantibus' in order to avoid any doctrinal implications. Instead, it referred to the rule as the doctrine of 'fundamental change of circumstances', 107 which was supposed to be 'an objective rule of law by which, on grounds of equity and justice, a fundamental change of circumstances may, under certain conditions, be invoked by a party as a ground for terminating the treaty'. 108 This approach, now enshrined in Article 62 VCLT and in the ILC commentaries, represents the dominant view today. 109 A proposal to integrate the vital interests theory into the VCLT by replacing the 'undue-burden' approach with the stricter standard that the change must have the effect of imperilling the State's existence was rejected at the Vienna Conference on the Law of Treaties. The attempt by Belarus to confine the doctrine to cases 'when a State found it completely impossible to perform a treaty, or where a treaty conflicted with its most vital interests', 110 did not gain support. As a result, the doctrine as codified in the VCLT represents a rejection of the proposition that imperilling a State's vital interests could by itself constitute a fundamental change of circumstances.

IV. CONCLUDING REMARKS
Notwithstanding contrary statements in the literature, the preceding discussion illustrates that the doctrine of rebus sic stantibus has indeed practical relevance today. Recent practice suggests, however, that States have returned to interpreting the doctrine by invoking changes in the domestic realm or vital State interests. The subsequent practice of Poland, Mongolia, Laos, Russia, Ukraine and Belarus in the application of Article 62 VCLT as supplementary means of interpretation under Article 32 VCLT, as well as the State practices of Poland and Cambodia concerning the doctrine as a matter of customary international law, demonstrate a willingness to regard changes in the constitutions of the invoking States as being a ground for the termination of treaties in accordance with the doctrine. The judgment of Ecuador's Constitutional Court represents a subsidiary means for the determination of the doctrine under customary international law to the same effect. The motions approved by the Kenyan Parliament point in a similar direction, although they may have limited legal value. Moreover, the practice of the US and Russia in connection with PDMA, as well as the practice of Denmark with respect to the Dublin regulations, reveals an understanding that links the doctrine to vital State interests. Argument of vital interests and the ones underlying the invocation of changes in the domestic sphere are kindred arguments. Some States consider that the values and norms enshrined in their constitutions reflect their respective vital interests.
These practices indicate a departure from the 'shared-expectations' approach which the ILC and the ICJ had adopted. They give priority to the adverse effects of the changes on the vital interests of one of parties, rather than to the frustrated common intentions of all the parties to treaty. Instead of confining the doctrine to changes which frustrate the object and purpose of the treaty, they open the door for changes which are not related to the object of the treaty as such. This makes it more difficult to predict which changes may constitute a fundamental change of circumstances and opens the door for subjective determinations by the invoking State. It is this line of reasoning that led Lauterpacht to state that '[f]rom Spinoza to modern deniers of international law, the doctrine rebus sic stantibus has been appealed to not only as a consequence, but also as the very proof of the States' independence of law'. 111 Yet the promise behind every treaty demands good faith performance: Pacta sunt servanda. A treaty is worth nothing if it is not kept and if it cannot be relied on. Compromising the sanctity of treaties compromises international law's ability to regulate the behaviour of its legal subjects.
The invocation of the doctrine in conjunction with vital State interests has to be seen against the backdrop of a broader tendency to contest rules of international law on the basis of arguments premised on vital interests and other sovereignty-related concerns. First, national security exceptions and derogation clauses in time of emergency have recently gained prominence in practice. 112 The nexus between these clauses and the doctrine is remarkable. The WTO Dispute Panel has only just found that the security exception stipulated in Article XXI(b)(iii) General Agreement on Tariffs and Trade 113 'acknowledges that a war or other emergency in international relations involves a fundamental change of circumstances which radically alters the factual matrix in which the WTO-consistency of the measures at issue is to be evaluated'. 114 Second, arguments based on constitutional identity that seek to pose limits to the binding force of international legal rules can be found in the reasoning of numerous constitutional court decisions. 115 These types of arguments display a kinship to vital interests and States' rights. 116 Third, the current backlash against international adjudication is also often accompanied