Under the law of treaties, two mechanisms currently seek to bridge the gap between the conclusion and entry into force of treaties. These are found in Article 18 (the obligation not to defeat the object and purpose of a pending treaty) and Article 25 (provisional application of treaties) of the Vienna Convention on the Law of Treaties. This article considers the nexus and relationship between these provisions and clarifies two aspects of their interaction. First, the article assesses how Articles 18 and 25 interact in their practical application and whether Article 25 can inform the content and interpretation of Article 18. Second, the article explores how the termination of a provisionally applied treaty under Article 25(2) affects the applicability of Article 18(a).

This article presents a theoretical framework by which to understand how disasters are reconciled with a state’s existing obligations under international law. This ‘reactive’ model of disaster regulation hinges on two regulatory techniques, ‘disapplication’ and ‘exculpation’, both of which involve a deviation from the ordinary application of a norm owing to the occurrence of a disaster or to measures adopted by a state in relation to it. It proceeds to outline the various doctrines and mechanisms across different subfields of international law, including international human rights law, investment law and trade law, which may operationalize these techniques in disaster situations. Finally, it argues that the applicability of certain disapplication and exculpation mechanisms to disasters relies on an anachronistic view of such disasters as rare and episodic occurrences beyond human control. This puts these mechanisms at odds with the central objectives of international disaster law and their underlying sociological and scientific premises, which emphasize the need for an ‘adaptive’ model of comprehensive and prevention-oriented disaster regulation. Accordingly, this analysis exposes the conceptual limitations of the reactive model for disaster regulation and explains and validates the inclination toward an adaptive model within international disaster law. It also indicates how mechanisms within the reactive model could be recalibrated to better regulate disasters.

The decision of the Court of Justice of the European Union in Slovak Republic v Achmea dealt a major blow to the predictability of the legal regime for the protection of foreign investments, whilst failing to offer a realistic, clear and sustainable solution for the protection of investments within the European single market. Commentators have mainly considered its implications from the perspective of the European Union or International Investment Law, and the potential conflict of regimes. This article offers a different approach, arguing that a reading of Achmea based on a moderate version of legal pluralism could adequately respond to the legitimate concerns about the case from both international and European legal perspectives. It is argued that the imprecision of the decision is in fact constructive ambiguity, allowing a sufficient margin of appreciation for all stakeholders and avoiding direct confrontation between the European and international legal orders. Recent developments, such as the innovative EU agreement for the termination of intra-EU BITs, point to new opportunities for ordering pluralism in the Achmea saga.

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.

In his Fourth Report on the Identification of Customary International Law (2016), Special Rapporteur Sir Michael Wood confirmed that ‘[i]n certain cases, the practice of international organizations also contributes to the expression, or creation, of rules of customary international law’. That the practice of international organizations can be relevant when identifying customary international law is relatively uncontroversial. The issue that is more debated is the extent to which the practice of international organizations as such may contribute to the development of customary international law. Using examples from the European Union's treaty practice and from the Court of Justice of the European Union, this article argues that international organizations may contribute to such practice, not only by representing the collective will of States, but as autonomous actors in their own right.

When interpreted, sometimes treaties have to go through a trial by fire and are found either to be ‘living instruments’ evolving alongside the relevant changes both in law and in facts or to have a ‘fixed’ meaning. The aim of the present article is to examine how intertemporal considerations find their way into the interpretative process and what the effects are on the treaties being interpreted. Do these changes in law and fact actually change the treaty itself, or do they merely trigger a latent quality already existing in the treaty itself? Does time change the treaty, or does it merely ‘unfold’ it? This question will be examined through the lens of the main philosophical theories on identity, persistence, time and change (endurantism, perdurantism and exdurantism), and by focusing on the ‘direct’ (principle of contemporaneity and evolutive interpretation) and ‘indirect’ (Article 31(3)(c) and the intertemporal application of the rules of interpretation) points of entry of intertemporal considerations in the interpretative process. Through this examination the elements that weigh upon the judicial interpretative process and tip the scales either in favour of an evolutive interpretation or in favour of the principle of contemporaneity, will be identified, as well as the limits of any such interpretation. In this manner, an answer will be arrived at as to whether, from an interpretative perspective, treaties endure, perdure or exdure.

This article compares and contrasts the interpretation of the Lusaka Ceasefire Agreement 1999 by the International Court of Justice, the Peace Agreement between the Government of Sierra Leone and the Revolutionary United Front of Sierra Leone by the Special Court for Sierra Leone, and the General Framework Agreement for Peace in Bosnia and Herzegovina by the European Court of Human Rights. In doing so, it critically analyses the approach of the three different tribunals and attempts to explain the differences identified on the basis of the jurisdictional scope of each tribunal and the substantive law each has been tasked to apply. This comparison is both substantive and procedural. The article then examines the impact of these three tribunals on two specific aspects of the rule of law: legal accountability and legal certainty, both internationally and in the countries under examination. It is argued that, while these tribunals have enhanced legal certainty and accountability on the international level, any contribution they have made to the domestic rule of law has been questionable.

For over three decades, it has been the International Law Commission's position that the circumstance of consent involves something other than the consent which, through the rule pacta sunt servanda, imparts objective force to international agreements. During the tenure of the second Special Rapporteur on the law of state responsibility, Roberto Ago, the Commission adopted the view that the former suspends the international obligations which are incumbent on states whereas the latter functions to create, modify, or extinguish the rules whence such obligations stem forth. However, as the result of the study carried out by its last Special Rapporteur, James Crawford, the Commission has now come to distinguish between the circumstance of consent defined as a justification for non-performance of subsisting obligations, and consent defined as a requirement for the application of obligations. In this contribution, it is argued that both analyses are problematic. The former gives succour to a mistaken view of the sources of international law. The latter is based on a misunderstanding of the primary-rule–secondary-rule terminology; it justifies itself by referring to an ill-conceived definition of the notion of peremptory norms, and no less importantly undermines the purposefully cumbersome mechanism envisaged in the 1969 Vienna Convention on the Law of Treaties for suspension of multilateral treaties as between certain of the contracting parties only.

The Comprehensive Nuclear Test Ban Treaty (CTBT) will not be effective until all the 44 states listed in its Annex 2 ratify it. A special link has been established between the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and the CTBT. The disarmament obligation set by Article VI of the NPT, which has not yet been complied with, remains highly controversial. The relevant subsequent practice of the states parties to the NPT shows that the ratification of the CTBT is to be considered the first of the practical steps towards compliance with Article VI. However, as the practical steps do not set any legally binding norms, there is no legal obligation to ratify the CTBT, not even for the 44 states listed in Annex 2 whose ratification is essential. The paper deals with the position of nuclear powers party to the NPT that have not yet ratified the CTBT (most prominently the US and China) and demonstrates that these states should at least provide detailed motivation for their conduct. Otherwise, other states parties to the NPT could consider them as not complying in good faith with Article VI of the NPT and invoke the inadimplenti non est ademplendum rule to justify breaches of their own obligations under the same treaty.

Stability versus change is one of the fundamental debates of the law of treaties. The limits of pacta sunt servanda – under which conditions a state may derogate from treaty obligations when circumstances change – appears as a constant throughout the history of international law. This article examines the limits of pacta sunt servanda in times of fragmentation. It first discusses the mechanisms of general international law – supervening impossibility of performance and fundamental change of circumstances (Articles 61 and 62 VCLT) in the law of treaties and force majeure and the state of necessity (Articles 23 and 25 of the ILC Articles on State Responsibility) in the law of state responsibility. It is argued that they provide only insufficient means to accommodate change. Against that background, derogation is examined in specific treaty regimes, including international human rights law, the law of the sea, and international investment law. Treaty-based termination/withdrawal clauses and emergency exceptions are analysed accordingly. Especially the latter are formulated in a regime-specific way, adapting derogation from treaty obligations to the requirements of the respective treaty regimes. On the basis of an empirical analysis of relevant state practice it is argued that this regime-specificity – a sign of fragmentation – is especially important since there is an increased need for temporary derogation in contemporary international law.