Compliance signifies conduct which is in accordance with international law. It includes refraining from acts not in accordance with international law, it may also require positive action to live up to certain international law obligations, and it is thus linked to the issue of implementation. International law provides for a number of means, mechanisms, and procedures to persuade those addressed by it to live up to their commitments. These are generally referred to as enforcement measures, and include dispute settlement and sanctions. However, a number of other means, such as verification, monitoring, and assessment measures, have also been developed. Furthermore, criminal sanctions, state responsibility and liability, while primarily aiming at doing justice and compensating in cases of a violation of the law, may, to some extent, also foster compliance.

In the absence of a uniform lawmaking and enforcement authority that is supreme in legitimation and power, the international legal system relies on States, which are equal in their sovereignty, to create and enforce its rules. Thus, States are at the same time creators of and subject to international law. In order to ensure compliance and thus to safeguard effectiveness, such a system may rely on institutions or individual States. The international legal system contains a number of institutions and procedures which address the task of settling disputes and in some cases may even authorize sanctions or enforcement action against individual States or groups of States.