However, the term most frequently used in a generic sense, whether to promote the concept or to criticize it, is lex mercatoria. At the risk of adding to the confusion, and with little hope of being able to impose definitive meanings for each expression, we shall simply give the meaning attributed to each of those expressions as used hereafter. Indeed, the terminological debate is only important in so far as it facilitates discussion, on a substantive level, of the way in which the various concepts fit together.
To denote rules other than those of a given jurisdiction, we shall use the generic expression lex mercatoria. The expression appears essentially in academic writing, and it covers not only transnational rules (which can only be described negatively as all rules which do not originate exclusively from a particular national legal system), but also international trade usages (meaning the practices usually followed in a particular trade).
In general, we prefer the term "transnational rules" to "a-national rules" because such rules derive from the convergence of the main legal systems from which they are drawn. It is therefore counterintuitive to suggest that they have no link with national legal orders. Transnational rules in turn embrace two separate concepts: first, rules which are common to several legal systems, determined on the basis of the tronc commun method; and second, general principles of international trade law.
Unitermos: arbitragem, lex mercatoria, comércio internacional.Revista Brasileira de Arbitragem