International law, also known as "law of nations", refers to the body of rules which regulate the conduct of sovereign states in their relations with one another. Sources of international law include treaties, international customs, general widely recognized principles of law, the decisions of national and lower courts, and scholarly writings. They are the materials and processes out of which the rules and principles regulating the international community are developed. They have been influenced by a range of political and legal theories.
Article 38(1) of the Statute of the International Court of Justice is generally recognized as a definitive statement of the sources of international law. It requires the Court to apply, among other things, (a) international conventions, whether general or particular, establishing rules expressly recognized by the contesting states; (b) international custom, as evidence of a general practice accepted as law; (c) the general principles of law recognized by civilized nations; (d) subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rules of law.
During the 19th century, it was recognized by legal positivists that a sovereign 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, and was later preserved in Article 38(1) of the 1946 Statute of the International Court of Justice.
The core of broad principles of law is general and dynamic, and they can sometimes be reduced to a proverb or a basic idea. Unlike other types of regulations, such as ordered law or agreements, broad standards of law have not been "established" according to the right sources of law. General norms of law, on the other hand, are regarded as a component of positive law, even if they are only used as auxiliary devices.