How did Roman law continue to apply to Roman subjects under Germanic rulers?

Following the fall of the Western Roman Empire, Germanic rulers did not attempt to impose their own tribal customs on their Roman subjects. Instead, they maintained a system of legal pluralism where Roman law remained applicable to the Roman population.1

Because Germanic law was traditionally personal—applying only to members of a specific tribe—it existed alongside the existing Roman legal frameworks. To facilitate this, Germanic kings issued specific codes for their Roman subjects, often based on "vulgar law," which was Roman law adapted to the social and economic conditions of the late empire. Notable examples include:1

• Lex Romana Visigothorum: Also known as the Breviary of Alaric, this code was issued in 506 CE to serve the needs of the Roman population under Visigothic rule.12
• Lex Romana Burgundionum: This served a similar function for Roman subjects within the Burgundian kingdom.1

This separation of laws persisted until the two populations began to fuse, eventually leading to the application of unified codes in later centuries. Additionally, the Roman Catholic Church continued to operate under Roman law, which heavily influenced the development of canon law.13