Its legal system is based on Spanish civil code (similar to the State of Louisiana) versus the system of Common Law practiced in the United States.

Puerto Rico became a U.S. territory in 1898 after four centuries as a Spanish colony. Its democratic form of government (subject to the U.S. Constitution was ratified and approved by the U.S. Congress 7/3/52) is that of a commonwealth associated with the U.S. consisting of three branches: Executive, Legislative and Judicial. Its indigenous inhabitants have been U.S. citizens since 1917 without the right to vote in U.S. presidential elections and likewise they pay no federal income taxes. An estimated 200,000 Puerto Ricans, many of them volunteers, have served in the U.S. Armed Forces since World War I. Its capital, San Juan, is one of 78 municipalities with elected Mayors. Island residents elect the Governor every 4 years. The Island residents also elect a non-voting representative (Resident Commissioner) to the U.S. House of Representatives to lobby for Puerto Rico's interests.