[1] Puerto Rico is the only current U.S. jurisdiction whose legal system operates primarily in a language other than American English: namely, Spanish.
Many of the Laws of Puerto Rico (Leyes de Puerto Rico) are modeled after the Spanish Civil Code, which is part of the Law of Spain.
[2] After the U.S. government assumed control of Puerto Rico in 1901, it initiated legal reforms resulting in the adoption of codes of criminal law, criminal procedure, and civil procedure modeled after those then in effect in California.
Although Puerto Rico has since followed the federal example of transferring criminal and civil procedure from statutory law to rules promulgated by the judiciary, several portions of its criminal law still reflect the influence of the California Penal Code.
As Puerto Rico is under United States sovereignty, U.S. federal law applies in the territory, and cases of a federal nature are heard in the United States District Court for the District of Puerto Rico.