The Louisiana political and legal structure has maintained several elements from the times of French and Spanish governance. One is the use of the term "parish" (from the French: paroisse) in place of "county" for administrative subdivision. Another is the legal system of civil law based on French, German and Spanish legal codes and ultimately Roman law—as opposed to English common law. Common law is "judge-made" law based on precedent, and is the basis of statutes in all other U.S. states. Louisiana's type of civil law system is what the majority of nations in the world use, especially in Europe and its former colonies, excluding those that derive from the British Empire.
Although the Napoleonic Code strongly influenced Louisiana law, it was never in force in Louisiana, as it was enacted in 1804, after the Louisiana Purchase of 1803. Differences still exist between Louisianan civil law and the common law found in the other U.S. states. While some of these differences have been bridged due to the strong influence of common law tradition, it is important to note that the "civilian" tradition is still deeply rooted in most aspects of Louisiana private law. Thus property, contractual, business entities structure, much of civil procedure, and family law, as well as some aspects of criminal law, are still mostly based on traditional Roman legal thinking.