United States

• The U.S. Constitution, the highest law, and each state's own constitution
• Statutes passed by Congress and by the state legislatures
• Regulations made by government agencies under those statutes
• Judges' decisions (precedent), which explain and develop all of the above

• Federal: the Supreme Court, then the regional courts of appeals, then the district (trial) courts
• State: each state has its own trial courts, usually an appeals court, and a state supreme court (the name varies)
• State courts decide most cases. Federal courts hear cases about federal law and some disputes between citizens of different states

Usually a four-year college degree, then three years of law school for the Juris Doctor (J.D.), then a bar exam. Lawyers are admitted state by state.

• Federalism: contract, tort, property and most criminal law are mainly state law, so the answer can change when you cross a state line.
• Judicial review: courts can strike down laws that conflict with the Constitution (the idea comes from Marbury v. Madison, 1803).
• Juries are used in many civil cases as well as criminal ones.
• There is no separate profession of barrister: one lawyer can usually do all the work, in or out of court.

United Kingdom, Canada, Australia, India, Ireland

The University of Ottawa’s JuriGlobe database lists United States as: Common law. It names the systems in order of importance.

The map colours a country by the first-named system, and shows both civil-law and common-law countries as “mixed”. It is a simplification, and real systems are rarely pure.

Antigua and Barbuda, Australia, Bahamas, Barbados, Belize, Canada, Cook Islands, Dominica, Fiji, Ghana, Grenada, India, Ireland, Jamaica.

• U.S. Courts: Court Role and Structure
• Supreme Court of the United States
• JuriGlobe: United States of America

Sources last reviewed: October 2026.