International law is the set of rules generally regarded and accepted as binding in relations between states and nations. It differs from national legal systems in that it only concerns nations rather than private citizens. National law may become international law when treaties delegate national jurisdiction to supranational tribunals such as the European Court of Human Rights or the International Criminal Court. Treaties such as the Geneva Conventions may require national law to conform.

The term "international law" can refer to three distinct legal disciplines:

The two traditional branches of the field are:

All sources of international law are from treaties and covenants which regulate relations between nations. They 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.

Stephen Gerald Breyer ( /ˈbraɪər/; born August 15, 1938) is an Associate Justice of the U.S. Supreme Court. Appointed by President Bill Clinton in 1994, and known for his pragmatic approach to constitutional law, Breyer is generally associated with the more liberal side of the Court.

Following a clerkship with Supreme Court Associate Justice Arthur Goldberg in 1964, Breyer became well known as a law professor and lecturer at Harvard Law School, starting in 1967. There he specialized in administrative law, writing a number of influential textbooks that remain in use today. He held other prominent positions before being nominated for the Supreme Court, including special assistant to the United States Assistant Attorney General for Antitrust and assistant special prosecutor on the Watergate Special Prosecution Force in 1973.

In his 2005 book Active Liberty, Breyer made his first attempt to systematically lay out his views on legal theory, arguing that the judiciary should seek to resolve issues to encourage popular participation in governmental decisions.

Martti Antero Koskenniemi (born 18 March 1953, Turku) is an international lawyer and a former Finnish diplomat. Currently he is professor of International Law in the University of Helsinki and Director of the Erik Castrén Institute of International Law and Human Rights. He is well known for his critical approach to international law. In 2008 - 2009 he held the seat of distinguished visiting Goodhart Professor at the Faculty of Law, Cambridge University. In 2011 Koskenniemi was Peace of Utrecht professor at Utrecht University.

Previously he has been Global Professor of Law in the New York University, and a member of the International Law Commission (2002–2006). He served in the Finnish Diplomatic Service in the years 1978-1996, lastly as director of the Division of International Law. He was Finland's counsel in the International Court of Justice in the Passage through the Great Belt case (Finland v. Denmark) (1991-2) [1].

In 1997 to 2003 he served as a judge in the administrative tribunal of the Asian Development Bank.