American common law vs British common law

English common law is the root — but America grew its own legal order from it. Getting this right means holding two true things at once: the states received English common law, and America then developed its own, at both the state and federal levels.

1. Reception: English common law came over — on each state’s terms

The original colonies, and later the states, received the English common law by reception statutes. Each state fixed its own reception date and terms, keeping English common law except where its own constitution and statutes changed it. So there is no single “American common law” inherited whole from England — there are fifty state common-law traditions, each with an English root and its own subsequent growth.

2. Federal courts: “there is no federal general common law”

On the federal side, the landmark is Erie Railroad Co. v. Tompkins, 304 U.S. 64 (1938). Justice Brandeis, overruling Swift v. Tyson (1842), held that when a federal court hears a state-law claim (in diversity), it must apply state law — there is no federal general common law for the federal courts to make up. That is the accurate, load-bearing statement of the rule.

“There is no federal general common law.” Erie R.R. Co. v. Tompkins, 304 U.S. 64 (1938) (Brandeis, J.).

3. But federal law is still made by federal courts — in two accurate senses

(a) Surviving federal-common-law enclaves. Erie ended general federal common law, not all of it. Federal courts still fashion common-law rules in narrow, genuinely federal areas — for example admiralty and maritime law, disputes between states, foreign relations, and the rights and duties of the United States itself.

(b) The federal judicial power over federal and constitutional questions. When the question is one of federal statute or the Constitution, the federal courts — with the Supreme Court at the top — are the authority, and their rulings bind nationwide. This is the accurate version of the idea that America has its own overriding body of national law: it is the federal judicial power over federal/constitutional law, not a free-floating “federal common law” of general subjects.

The ACA example: a national question, decided for the whole country

A clean illustration is National Federation of Independent Business v. Sebelius, 567 U.S. 519 (2012). The Court upheld the Affordable Care Act’s individual mandate — not under the Commerce Clause, but as a valid exercise of Congress’s taxing power (Chief Justice Roberts writing; decided June 28, 2012). Whatever one thinks of the result, it shows the mechanism: a federal court resolving a national, constitutional question, and that ruling binding every state. That is the federal judicial power at work — the accurate core of the “America has its own law” point.