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Thursday, 23 July 2020

Dr Lorand Bartels is a Reader in International Law in the Faculty of Law, a Fellow of the Lauterpacht Centre for International Law and a Fellow of Trinity Hall at the University of Cambridge where he teaches international law, WTO law and EU law. 

Dr Federica Paddeu is the John Tiley Fellow in Law at Queens’ College and a Fellow of the Lauterpacht Centre for International Law. Her main research interests are international law, the law of state responsibility and the law on the use of force. 


* Adapted from the Introduction to this volume.


In international law, as in every legal system, rules are invariably subject to exceptions. Our intention in producing this book was to investigate this phenomenon from both a theoretical and doctrinal perspective. To this end, we invited scholars from legal theory and from international law to engage in a process of cross-fertilisation of insights and experience.

Rules and exceptions

The book begins with several chapters identifying a conceptual understanding of the notion of a ‘rule’ to which an exception can apply. In its simplest form, a rule is a norm that, when its preconditions and internal conditions are satisfied, generates a specified outcome. Such outcomes can be of several types, and there can be more than one outcome for each rule. But no matter their type, these rules have one feature in common: there can be reasons why they are not applied, even when their preconditions and internal conditions are satisfied. Importantly, this is as true for definitional rules (for example, the status of territory acquired or statehood established as a result of an illegal use of force) as it is for rules specifying a normative outcome (for example, a use of force that is not prohibited when it is exercised in self-defence). And it is in these cases, when there is a reason for not applying a rule, that one can speak of an ‘exception’ being made to that rule.

Identifying exceptions

In some cases, it may be clear what is the rule, and what the exception to that rule. But this is not always the case. Thus, Methymaki and Tzanakopoulos examine the relationship between the rule that states can exercise jurisdiction over their territory, and the opposing rule that other states are immune from such jurisdiction (which is itself subject to exceptions). As they say, there is simply no way to say which of these is the rule, and which the exception, and this is because both are immediately derived from the basis of international law, namely state sovereignty.

In other cases, looking at a legal concept in terms of a rule-exception dyad can help to understand where that concept fits into a broader legal structure. Linderfalk shows that the duty to act in good faith is not a standalone obligation, but rather an exception to a right to act for a particular purpose. As such, a state cannot violate that duty; at most, the state cannot exercise its right. Likewise, Dolcetti and Ratti critique the ICJ’s ruling in Jurisdictional Immunities that the doctrine of state immunity is not affected by jus cogens norms.

In these examples, concepts sometimes seen as standalone are properly categorised as exceptions to rules. Sometimes there is more untangling to be done. This is the case with Article 2 of the International Law Commission’s Articles on State Responsibility, which states that ‘[t]here is an internationally wrongful act of a State when conduct consisting of an action or omission: … (b) constitutes a breach of an international obligation of the State.’ The problem is that Chapter V of the same Articles lists six ‘circumstances’ (consent, self-defence, countermeasures, force majeure, distress, and necessity) that ‘preclude [the] wrongfulness’ of the very same conduct. How, then, can conduct be both wrongful and, in certain circumstances, not wrongful? Duarte d’Almeida and Paddeu answer this conundrum by identifying a category of conduct that is incompatible with an obligation (when a rule applies) but that is still not wrongful (because one of the circumstances precluding wrongfulness applies).

Exceptions and scope limitations

Even when an ‘exception’, in the broad sense, can be identified, it can exist in a variety of different forms, explored by Viñuales. Nonetheless, as Sartor shows, these differences essentially resolve into two main types: conditions limiting the scope of application of a rule (scope limitations), and conditions deeming a rule not to apply for independent reasons (exceptions provisions). In turn, scope limitations can be positive (‘do not kill a person’ necessarily excludes mosquitos) or negative (‘do not kill animals except insects’), and they can also be internal or external (‘the rule on killing animals does not apply to insects’) – this can be called a carveout. In principle, as several authors note, the same result can be achieved by any of these means. What, then, are the differences?

Sartor emphasises that the rationales for scope limitations tend to be based on the rationale for the obligation, whereas rationales for exceptions tend to be different. However, other factors are also important. One is normative: As several contributors put it, there is a difference between the lawfulness of killing a mosquito, and killing a person in self-defence.

A normative priority for rules may also underlie the way that tribunals approach their task analytically. As Pauwelyn and Viñuales say, tribunals have a tendency to analyse rules before exceptions and, within rules, to consider scope limitations before dealing with the obligation itself. Frequently, this is justified on the grounds of logic: there is no reason to consider an exception to a rule unless there has been a breach. But of course, there is also no need to analyse an obligation to which an exception applies, and the reverse order of analysis has been adopted, for example in Continental Casualty v Argentina, Russia – Traffic in Transit, and Oil Platforms.

Alongside normative signalling, and its interpretive implications, there are also practical differences between scope limitations (whether internal or external) and exceptions. One important difference, which for Duarte d’Almeida is the defining difference, is the allocation of the burden of proof. Pauwelyn considers in detail the different burdens applicable to raising an issue, producing evidence, and persuading an arbiter, along with standards of proof and standards of review, and shows how these elements can be combined in different ways within rules and exceptions.

There is also at least one other situation in which it is substantively important to distinguish between a scope limitation and an exception, which is when a metanorm determines that a rule cannot have any exceptions. This presents a conundrum for jus cogens norms that are subject to conditions that, in other contexts, look rather like exceptions than scope limitations. De Hoogh tackles this conundrum from the perspective of theory and doctrinal practice, and after considering various options concludes that the jus cogens element of the prohibition must be limited to cases of aggression, which excludes cases of self-defence and consent, rather than the use of force more generally.

Rule preconditions

Finally, rules are only applicable in the first place when their preconditions are also met. The main precondition for the application for any rule is its validity. However, there are others; indeed, following Dolcetti and Ratti, there will be an absent precondition whenever a meta-norm authorising the application of a subordinate norm is itself disapplied. This can have extremely disruptive effects on the underlying legal system. Thus, Kolb explains that the doctrine rebus sic stantibus was at one point seen (at least by some) as an expression of the notion that the principle pacta sunt servanda ‘does not extend at all to inapplicable treaties (i.e. the ones contrary to the independence and vital interests of the State).’

This understanding of rebus sic stantibus is of course no longer current. But another remains, namely, a precondition that the addressee of the rule continues to exist, or, rather, would not exist if it did not act in a certain way. Schauer sets up the problem with a domestic example: a promise to make dinner is cancelled by the death of the promisor. Jeutner extends this by reference to the ICJ’s suggestion in Nuclear Weapons that the threat or use of nuclear weapons might not be illegal if the very survival of a state were at stake. For Jeutner, in such a situation, there would be a ‘legal dilemma’ insofar as the threat or use of nuclear weapons would be lawful, but would still be subject to the consequences of unlawfulness. Others, following Schauer, might say that the obligation is cancelled.


What emerges from this project is a firm conviction that legal concepts are best understood in terms of their formal position in an overall framework. If it is possible to represent the relationship between rules and exceptions in the form of flow charts, as does Sartor, then this must underpin any interpretation of what those rules and exceptions mean. Of course, law is more than simply logic – and, as our contributors show, in a detailed manner, whether a given norm is a rule or an exception (or even exceptions of different types) comes with political, moral and practical implications. What we hope also to have shown in this book, however, is that such issues have their own dynamic, and drive the characterisation of norms as rules or exceptions, rather than vice versa.