Henderson v. Moore was a case heard by the United States Supreme Court in 1809. The dispute arose when Henderson, an American citizen, sued Moore for breach of contract after he failed to pay for goods that had been shipped from England to America. In his defense, Moore argued that the contract between himself and Henderson was invalid because it violated a law passed by Congress which prohibited foreign trade with France during wartime. The court ultimately ruled in favor of Henderson on the grounds that while Congress did have authority over international commerce, they could not interfere with contracts already made prior to their enactment of such laws as this would be unconstitutional under Article I Section 10 Clause 1 of the Constitution which states "No State shall pass any Bill of Attainder or ex post facto Law". This ruling established precedent regarding Congressional power over interstate commerce and private contracts within its jurisdiction.

In Henderson v. Moore, the Supreme Court was asked to decide whether a contract between two parties could be enforced even if it violated state law. The majority of the court held that such contracts were not enforceable and should be declared void by courts of justice. However, Justice Chase dissented from this opinion and argued that contracts which violate state laws are still valid under federal common law unless they conflict with public policy or morals. He further stated that in cases where there is no clear violation of either public policy or morality, then such contracts should remain binding on both parties regardless of any conflicting state laws. Therefore, he concluded that the contract at issue in this case should have been enforced as written because it did not clearly violate either public policy or morality and thus was legally binding on both parties despite its potential violation of state law.