International law (also known as public international law and the law of nations) is the set of rules, norms, and standards that states and other actors feel an obligation to obey in their mutual relations and generally do obey. In international relations, actors are simply the individuals and collective entities, such as states, international organizations, and non-state groups, which can make behavioral choices, whether lawful or unlawful. Rules are formal, often written expectations for behavior and norms are less formal, customary expectations about appropriate behavior that are frequently unwritten.[1] It establishes norms for states across a broad range of domains, including war and diplomacy, economic relations, and human rights.
International law differs from state-based domestic legal systems in that it operates largely through consent, since there is no universally accepted authority to enforce it upon sovereign states. States and non-state actors may choose to not abide by international law, and even to breach a treaty but such violations, particularly of peremptory norms, can be met with disapproval by others and in some cases coercive action ranging from diplomatic and economic sanctions to war.
The sources of international law include international custom (general state practice accepted as law), treaties, and general principles of law recognised by most national legal systems. Although international law may also be reflected in international comity—the practices adopted by states to maintain good relations and mutual recognition—such traditions are not legally binding. The relationship and interaction between a national legal system and international law is complex and variable. National law may become international law when treaties permit national jurisdiction to supranational tribunals such as the European Court of Human Rights or the International Criminal Court. Treaties such as the Geneva Conventions require national law to conform to treaty provisions. National laws or constitutions may also provide for the implementation or integration of international legal obligations into domestic law.