Which U.S. Supreme Court case in 1944 ruled that insurance is interstate commerce?

United States v. South-Eastern Underwriters Association was the 1944 Supreme Court case that held qualifying insurance business across state lines to be interstate commerce.

Decided on June 5, 1944, the case involved a group of fire insurers accused of fixing premiums and restraining competition. The Court held that an insurer conducting substantial business across state lines was engaged in commerce among the states and that the Sherman Antitrust Act could apply. The ruling rejected the older approach associated with Paul v. Virginia, which had treated issuing an insurance policy as outside interstate commerce.

The decision did not simply turn insurance into a federally administered industry. It established that Congress could regulate interstate insurance activity, while leaving difficult questions about state and federal authority. Concern that the ruling might disrupt state regulation helped prompt Congress to pass the McCarran-Ferguson Act in 1945.

That statute preserved a central role for state insurance regulation and limited federal antitrust application in specified circumstances, while retaining federal authority in defined areas. Thus, the case is best remembered for recognizing interstate commerce and applying federal antitrust principles to insurance—not for abolishing state oversight.