The notion of third-party countermeasures, as embodied in Article 54 ARSIWA, is generally understood as a possible means of implementation of responsibility for breaches of communitarian norms, i.e. obligations erga omnes (partes) within the meaning of Article 48 ARSIWA. Responsibility may arise by operation of law, but its implementation is by no means automatic. Implementation of responsibility requires invocation (or standing) by way of a claim of a relatively formal character, including one made, in the terminology of Article 48 ARSIWA, by ‘a State other than the injured State’ in defence of a communitarian norm. Simply put, standing is primarily a ‘normative concept’ which seeks to distinguish a State's legally enforceable interests from other non-enforceable ones based on notions such as ‘right’, ‘injury’ and ‘legal interest’. The invocation or implementation of responsibility can take various forms; it may involve the presentation of a claim in a diplomatic setting, the commencement of proceedings before an international court or tribunal, or even the taking of (third-party) countermeasures.

The notion of standing is relevant in analytical terms to all such forms of law enforcement even if it does not necessarily apply in the same way. An entitlement to invoke responsibility in response to breaches of communitarian norms (whether by judicial proceedings or otherwise) may not automatically translate into an entitlement to take third-party countermeasures. The ILC affirms in Article 48 ARSIWA that States have standing to invoke breaches of communitarian norms, but in Article 54 ARSIWA, it leaves open the question of whether – and if so, in which circumstances – States may do so by way of third-party countermeasures. Indeed, standing to take third-party countermeasures – insofar as it exists at all – may well be subject to different and more stringent conditions (e.g. regarding the possible condition of a serious breach) than other less coercive forms of invocation of responsibility for breaches of communitarian norms. The basic point nevertheless remains intact: the general notion of standing in defence of community interests provides the analytical basis for an assessment of the contours of a possible entitlement to take third-party countermeasures.