Lex mercatoria and it's application

In our thesis study, international commercial custom and usages rules and their applications, which started to gain importance within the globalized world have been discussed. In this manner, first of all commercial custom and usages rules are discussed on the basis of our country?s legal system, and then lex mercatoria terms and finally Unidroit Principles are mentioned in the study.The main difficulties that has been experienced during our study, the issue?s being theoretically wide and the Court jurisprudences messy in application and the Arbitration Awards? being very hard to access.It has been concluded that the application of the rules (especially Unidroit Principles) in lex mercatoria and new lex mercatoria within all aspects is assumed to become widespread within the course of time due to edict autonomy principle in private law.