Because justices can serve for decades, a single appointment can shape constitutional law long after the president who nominated them has left office.
Supreme Court justices keep their jobs for as long as they want, with no set end date, unless they step down or are removed.
With no fixed end dates, the timing of deaths and retirements determines when seats open, making each vacancy a high-stakes political event.
Article III says federal judges 'shall hold their Offices during good Behaviour,' language courts and Congress have long read to mean service for life absent misconduct.
A justice can be removed only through impeachment by the House and conviction by a two-thirds vote of the Senate, a bar that has never been cleared for a Supreme Court justice.
A look at the constitutional rules, historical trends and reform proposals behind a debate over how long justices should serve.
Read the guide →A long-running debate over judicial tenure has gained new prominence amid proposals to cap justices' service at 18 years.
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