Article III states federal judges "hold their office during good behavior," which courts interpret as lifetime tenure removable only through impeachment and Senate conviction for treason, bribery, or other high crimes and misdemeanors.
Congress has impeached 15 federal judges since 1789, convicting eight, about one every 14 years. John Pickering lost his seat in 1804 for intoxication on the bench and mental instability. Alcee Hastings was removed in 1989 for perjury and bribery conspiracy, though he later won election to Congress.
The modern view rejects "good behavior" as a separate removal standard beyond impeachment. Congress has never removed a judge for legal or political disagreements, protecting judicial independence from legislative pressure. The Framers designed lifetime tenure to insulate judges from political retaliation when making unpopular but legally correct decisions.