International Law - Sources of International Law

Sources of International Law

A source of international law is where an international decision maker or researcher looks to verify the substantive legal rule governing a legal dispute or academic discourse. The sources of international law applied by the community of nations to find the content of international law are listed under Article 38.1 of the Statute of the International Court of Justice: Treaties, international customs, and general principles are stated as the three primary sources; and judicial decisions and scholarly writings are expressly designated as the subsidiary sources of international law. Many scholars agree that the fact that the sources are arranged sequentially in the Article 38 of the ICJ Statute suggests an implicit hierarchy of sources. However, there is no concrete evidence, in the decisions of the international courts and tribunals, to support such strict hierarchy, at least when it is about choosing international customs and treaties. In addition, unlike the Article 21 of the Rome Statute of the International Criminal Court, which clearly defines hierarchy of applicable law (or sources of international law), the language of the Article 38 do not explicitly support hierarchy of sources.

The sources have been influenced by a range of political and legal theories. During the 20th century, it was recognized by legal positivists that a sovereign state could limit its authority to act by consenting to an agreement according to the principle pacta sunt servanda. This consensual view of international law was reflected in the 1920 Statute of the Permanent Court of International Justice, which was succeeded by the United Nations Charter and is preserved in the United Nations Article 7 of the 1946 Statute of the International Court of Justice.