The Supreme Court declared that Congress’s investigative power and its derivative contempt power were limited to legislative not judicial purposes.

Justice Samuel F. MillerMiller, Samuel F.;Kilbourn v. Thompson[Kilbourn v. Thompson] wrote the unanimous opinion of the Supreme Court in this undated decision, holding that Congress may conduct investigations to obtain information only for future legislation and not for judicial purposes. For this reason, the congressional attempt to subpoena Hallett Kilbourn, hold him in contempt, and imprison him were improper. In later decisions, the Court did allow for punishment for contempt of Congress and also allowed a broader definition of the scope of legislative investigation.Contempt of Congress;Kilbourn v. Thompson[Kilbourn v. Thompson]Congressional power of investigation;Kilbourn v. Thompson[Kilbourn v. Thompson]

Congressional power of investigation

Contempt power of Congress

Separation of powers