Adam Clayton Powell Jr., a powerful Harlem congressman, was re-elected in 1966 but denied his seat by the House after committee findings of misconduct. The Court, in an opinion by Chief Justice Warren, rejected the political-question defense and held that the House's power to 'judge the Qualifications of its own Members' under Article I, § 5 is limited to the three qualifications the Constitution itself specifies — age, citizenship, and inhabitancy. Anything beyond that requires the far higher bar of expulsion by a two-thirds vote under § 5's separate expulsion clause. Powell is the definitive judicial rebuke of Congress trying to add qualifications by the back door, and it complements U.S. Term Limits v. Thornton (1995), which applied the same principle to states.