When local circumstances make it necessary, the states can regulate interstate commerce as long as such regulations do not conflict with federal law. State laws related to commerce powers can be valid if Congress is silent on the matter. Decided March 2, 1852 (argued 1852). Opinion of the Court: Benjamin Robbins Curtis → go there Dissenting: McLean. Topic: Federalism. Cooley v. Board of Wardens, 53 U.S. 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. Wiki link