The U.S. Constitution as adopted in 1789 defines a structure of elected officials operating as a presidential republic. The Constitution enumerates the powers of the government and guarantees fundamental rights of the people. It explicitly reserves anything not mentioned to the states or the people themselves. Over time the federal government has taken an active role in many aspects of life not anticipated by the Constitution.

English common law is the basis for federal, state and local law in forty nine states. Louisiana law derives from the Napoleonic Code. Courts, attorneys and police operate at local, state and federal levels to interpret and enforce the law.

The states have all adopted governments structured like the national government with a written constitution, independent executive, legislative and judiciary branches. Other representative democracies around the world show much greater variety of structure.