Lex mercatoria

Lex mercatoria (from Latin for "merchant law"), often referred to as "the Law Merchant" in English, is the body of commercial law used by merchants throughout Europe during the medieval period. It evolved similar to English common law as a system of custom and best practice, which was enforced through a system of merchant courts along the main trade routes. It developed into an integrated body of law that was voluntarily produced, adjudicated and enforced on a voluntary basis, alleviating the friction stemming from the diverse backgrounds and local traditions of the participants. Due to the international background local state law was not always applicable and the merchant law provided a leveled framework to conduct transactions reducing the preliminary of a trusted second party. It emphasized contractual freedom and inalienability of property, while shunning legal technicalities and deciding cases ex aequo et bono. With lex mercatoria professional merchants revitalized the almost nonexistent commercial activities in Europe, which had plummeted after the fall of the Roman Empire.

In the last years new theories had changed the understanding of this medieval treatise considering it as proposal for legal reform or a document used for instructional purposes. These theories consider that the treatise cannot be described as a body of laws applicable in its time, but the desire of a legal scholar to improve and facilitate the litigation between merchants. The text is composed by 21 sections and an annex. The sections described procedural matters such as the presence of witnesses and the relation between this body of law and common law.