International trade law includes the appropriate rules and customs for handling trade between countries. However, it is also used in legal writings as trade between private sectors. This branch of law is now an independent field of study as most governments have become part of the world trade, as members of the World Trade Organization (WTO). Since the transaction between private sectors of different countries is an important part of the WTO activities, this latter branch of law is now part of the academic works and is under study in many universities across the world.

International trade law should be distinguished from the broader field of international economic law. The latter could be said to encompass not only WTO law, but also law governing the international monetary system and currency regulation, as well as the law of international development.

The international trade law includes rules, regulations and customs governing trade between nations. International trade law is the tool used by the nation’s government for taking corrective actions against trade. International trade law focuses on applying domestic rules to international trade rules and applying treaty-based international trade law governing trade.

The body of rules for transnational trade in the 21st century was derived from medieval commercial laws called the lex mercatoria and lex maritima—respectively, "the law for merchants on land" and "the law for merchants on the sea." Modern trade law (extending beyond bilateral treaties) began shortly after the Second World War, with the negotiation of a multilateral treaty to deal with trade in goods: the General Agreement on Tariffs and Trade (GATT).

International trade law is based on theories of economic liberalism developed in Europe and later the United States from the 18th century onwards.

International Trade Law is an aggregate of legal rules of "international legislation" and new lex mercatoria, regulating relations in international trade. "International legislation" – international treaties and acts of international intergovernmental organizations regulating relations in international trade. lex mercatoria – "the law for merchants on land". Alok Narayan defines "lex mercatoria" as "any law relating to businesses" which was criticised by Professor Julius Stone. and lex maritime – "the law for merchants on sea. Alok in his recent article criticised this definition to be "too narrow" and "merely-creative". Professor Dodd and Professor Malcolm Shaw of Leeds University supported this proposition.^{[citation needed]}

The Lex Mercatoria is the grouping of legal rules that guide and underlie international trade, which acts totally independently of the positive law of states, being considered normative. Currently, the new Lex Mercatoria has been prepared. The former Lex Mercatoria was generated in light of the characteristic demands of the time in question, including the values, culture, and future provisions of the time, whereas, the new one is recognized as having the responsibility of common international trade law.

In 1995, the World Trade Organization, a formal international organization to regulate trade, was established.^{[citation needed]}