Legal history of the Catholic Church
The Catholic Church utilizes the oldest continuously functioning legal system in the West, much later than Roman law but predating the evolution of modern European civil law traditions. The history of Latin canon law can be divided into four periods: the jus antiquum, the jus novum, the jus novissimum and the Code of Canon Law.
Source: Wikipedia — Legal history of the Catholic Church (CC BY-SA 4.0)