International law also known as 'law of nations' is the name of a 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 principles of law as recognized by civilized nations, 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. International law also known as 'law of nations' is the name of a 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 principles of law as recognized by civilized nations, 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. The sources of international law can be found in Article 38.1 of the Statute. This portfolio of sources was extracted from Article 38 of the original world court's constitutive statute. 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. On the question of preference between sources of international law, rules established by treaty will take preference if such an instrument exists. It is also argued however that international treaties and international custom are sources of international law of equal validity; this is that new custom may supersede older treaties and new treaties may override older custom. Also, jus cogens (peremptory norm) is a custom, not a treaty. Certainly, judicial decisions and juristic writings are regarded as auxiliary sources of international law, whereas it is unclear whether the general principles of law recognized by 'civilized nations' should be recognized as a principal or auxiliary source of international law. Nevertheless, treaty, custom, and general principles of law are generally recognized as primary sources of international law. Treaties and conventions are the persuasive source of international law and are considered 'hard law.' Treaties can play the role of contracts between two or more parties, such as an extradition treaty or a defense pact. Treaties can also be legislation to regulate a particular aspect of international relations or form the constitutions of international organizations. Whether or not all treaties can be regarded as sources of law, they are sources of obligation for the parties to them. Article 38(1)(a) of the ICJ, which uses the term 'international conventions', concentrates upon treaties as a source of contractual obligation but also acknowledges the possibility of a state expressly accepting the obligations of a treaty to which it is not formally a party.