U.S. Law & Constitution
Explainers on how the U.S. Constitution, federal lawmaking, and the broader American legal system work.
The U.S. legal system rests on a written Constitution that creates three branches of government, divides power between the federal government and the states, and sets out the process by which a bill becomes law. This hub is a plain-language starting point for understanding that structure — not a substitute for reading the Constitution itself or consulting a lawyer about how it applies to a specific situation.
The Three Branches and How Laws Are Made
Article I of the Constitution vests legislative power in Congress (the House of Representatives and the Senate), Article II vests executive power in the President, and Article III vests judicial power in the Supreme Court and the lower federal courts Congress establishes. A federal bill generally must pass both chambers of Congress in identical form and then be signed by the President — or, if vetoed, be repassed by a two-thirds vote in each chamber — before it becomes law. Our guide on the U.S. Constitution and how federal laws are made walks through that process from committee to signature.
Federal, State, and Local Law Together
The United States doesn't have one legal system — it has more than fifty overlapping ones: federal law applies nationwide on matters within federal power, each state has its own constitution, legislature, and courts, and cities and counties add local ordinances on top. Which law governs a given question depends on which government has authority over that subject matter, and more than one level can apply to the same situation at once. Our guide on how the U.S. legal system works covers how these layers relate, plus the basics of civil versus criminal cases and the role of courts, judges, and juries.
Why "How Many Laws Are There?" Doesn't Have a Simple Answer
People often expect a single number, but there is no authoritative count of "all U.S. laws": federal statutes, federal regulations, and the statutes and regulations of fifty states and thousands of local governments would all need to be counted using a consistent definition of "a law" that doesn't really exist. Our guide on how many laws there are in the U.S. explains why the commonly repeated figures don't hold up and what can actually be measured.
Key Terms
Statute — a law passed by a legislature. Precedent / stare decisis — the principle that courts generally follow prior decisions on the same legal question. Judicial review — the power of courts, established in Marbury v. Madison (1803), to strike down laws that conflict with the Constitution. Codified law — statutes organized by subject into a code, such as the U.S. Code.
Related Legal Areas
The First Amendment's religion clauses and how U.S. courts apply the Constitution to unusual legal disputes are covered in more depth in our Religion, Law & Weird Laws hub. For how lawyers are trained and licensed within this system, see Legal Education & History.
Authoritative Sources & Further Reading
- National Archives — The Constitution of the United States — the full, official text.
- Congress.gov — the official record of federal bills, statutes, and legislative activity.
- United States Courts (uscourts.gov) — how the federal court system is organized and how cases move through it.
- GovInfo (U.S. Government Publishing Office) — official federal statutes, regulations, and the U.S. Code.
Last updated August 11, 2026. This page provides general legal and civic information and does not constitute legal advice. Read our full legal disclaimer.
