International law is a set of rules and principles governing the relations and conduct of sovereign states with each other, as well as with international organizations and individuals. Issues that fall under international law include trade, human rights, diplomacy, environmental preservation, and war crimes. Different international bodies, such as the United Nations and World Trade Organization, are responsible for overseeing these issues. Generally speaking, the goal of international law is to promote peace and order between nations.
International law largely operates upon the consent of participating nations because no governing body exists to explicitly enforce international agreements. The Charter of the United Nations is the document that expounds upon international law, but the United Nations cannot enforce those laws directly in the same way that a sovereign state can enforce its laws domestically. Additionally, international law has no bearing on domestically enforceable law recognized by courts in the United States, barring legislation by Congress that incorporates international legal principles into domestic law. Although international law is not strictly enforceable upon nations or other international actors, treaties and the possibility of economic sanctions work to create heavy incentives for abiding by international law.
Public international law governs the relations between nations and sets forth mandates for those nations to abide by. On the other hand, private international law deals with conflicts between private actors in situations where more than one nation’s laws may apply. In recent years, public and private international law have become less distinct from one another. Disputes between private actors often implicate matters of public international law, and public international law likewise bears heavily on private actors, particularly multinational corporations.
Domains of International Law
International law includes concepts of law—such as statutes, property law, and tort law—that are common in many Western domestic legal systems. Substantive law, procedural law, due process, and remedies are also key facets of international law. The following are some of the central subsets of international law:
- International economic law
- International security law
- International criminal law
- International environmental law
- Diplomatic law
- International humanitarian law
- International human rights law
Sources of International Law
Article 38 of the Statute of the International Court of Justice lists four principal sources of international law: conventions/treaties, customary law, general principles of law, and judicial decisions/scholarly articles.
Treaties are binding agreements between nations that govern the rights and obligations of participating countries. The use of international conventions, i.e., treaties, was codified in the 1969 Vienna Convention on the Law of Treaties. Sovereign states use treaties to cooperate on various issues such as military defense, environmental conservation, and trade. International treaties generally cannot conflict with domestic law in participating nations.
Customary law arises from patterns of behavior in nations. States follow certain practices for a period of time out of a sense of legal obligation, and those practices develop into international law. For example, most nations have agreed to prohibitions on genocide and certain egregious forms of torture.
General principles of law are aspects of common law that are shared by most countries in the world. Because these foundational principles are shared familiarly between most countries, they enter into the realm of international law as well.
Rarely, judicial decisions and scholarly articles play a role in international law when the prior three sources of law fail. For example, a tribunal such as the International Criminal Court may refer to judicial decisions of the nations in question if there is no clear rule found in international law.
Federal Material
U.S. Constitution
- Article I, Section 8 - Congress' power to regulate commerce among the nations
- Article I, Section 10 - Limitation on states' power to conduct foreign relations
- Article II, Section 2 - Executive power to negotiate treaties
- Article III, Section 2 - Judicial power to resolve disputes involving an international party
- Article IV - Treaties of the United States
- CRS Annotated Constitution
Federal Statutes
- U.S. Code: 22 U.S.C. Foreign Relations and Intercourse
International Material
Conventions and Treaties
- Collection of Treaties
- UN Charter
- The European Union
- GATT
- The Rome Statute of the International Criminal Court
International Organizations
- United Nations
- International Court of Justice
- NATO
- Partnership for Peace Members
- International Monetary Fund
- International Federation of Red Cross and Red Crescent Societies
- World Bank
- World Trade Organization
- World Health Organization (WHO)
- International Criminal Court
Additional Resources
- Department of State
- Journals
- Cornell International Law Journal
- Harvard International Law Journal
- Indiana Journal of Global Legal Studies
- Stanford Journal of International Law
- Yale Journal of International Law
- GlobaLex
- International Affairs Web Resources
- A-Z Resources on International Law
- LII: World Law Collection
[Last updated in July of 2023 by the Wex Definitions Team]