Cooley v. Board of Wardens, 53 U.S. (12 How.) 299 (1852), was a US Supreme Court case that held that a Pennsylvania law requiring all ships entering or leaving Philadelphia to hire a local pilot did not violate the Commerce Clause of the US Constitution. Those who did not comply with the law had been required to pay a fee.
Benjamin R. Curtis wrote for the majority, "It is the opinion of a majority of the court that the mere grant to Congress of the power to regulate commerce, did not deprive the States of power to regulate pilots, and that although Congress had legislated on this subject, its legislation manifests an intention, with a single exception, not to regulate this subject, but to leave its regulation to the several states."
The legal historian Charles W. McCurdy viewed Cooley as a defining case, which clarified the Court's hitherto-contradictory jurisprudence on state powers over interstate commerce.