What Are the Four Main Sources of American Law?

The four main sources of American law are statutes and ordinances, Constitutional law, administrative law and common law. Treaties are also considered a source of law. Most of U.S. law consists primarily of state law, as regulations and bills often differ between states.

Each source of the law is derived from a different authority. Constitutional law derives from the U.S. Constitution. Statutory law is based on written law created by a legislature, as opposed to one person in power. Administrative law refers to the legislative agencies, and common law refers to decisions handed down by judges that establish precedent for future legal decisions.