Lex Mercatoria Law and Legal Definition

Lex mercatoria refers to a body of oral, customary mercantile law which developed in medieval Europe and was administered quite uniformly across Europe by merchant judges, adjudicating disputes between merchants. In the contemporary world, some scholars believe that there exists a modern lex mercatoria, defined to include certain transnational trade usages and commercial customs recognized internationally by the mercantile community.

In addition, lex mercatoria also extends to certain international conventions and even national laws pertaining to international economic relations. International commercial arbitration is frequently cited as a field in which the modern lex mercatoria is operative.

In The CHAMPION, 1874 U.S. Dist. LEXIS 134 ( E.D. Mich. 1874), it was held that lex mercatoria is a part of the common law, unless it be altered or controlled by parliament or the municipal courts.