This article aims to inform the development of Thai law and courts in the reign of King Chulalongkorn until the change of government in B.E. 2475. Because, in the Ayutthaya period to the reign of King Chulalongkorn (Rama 5), there was the Phra Thammasat Scripture as the master law and there were many courts according to various departments. The punishment used the metropolitan tradition. As a result, foreigners refused to attend Thai courts.

The reign of King Chulalongkorn (Rama 5) has reformed the law, set up a committee to draft a criminal law, Assoc. 127. Later, the name was changed to the Criminal Code and created the Civil Code to make it internationally recognized by foreigners. In addition, the courts in various departments were gathered at the Ministry of Justice and establishing law schools. As a result, the name of the law and the courts, as well as the punishment, has changed.