"All federal judges appointed under Article III of the Constitution have lifetime tenure.
They hold office, as the Constitution states, “during good Behaviour” or until they choose to step down.
The only way to remove them from the bench is through impeachment and conviction, a two-step process by which federal judges (and also the President, Vice President, “and all civil Officers of the United States”) can be removed from office for “Treason, Bribery, or other high Crimes and Misdemeanors.”
Impeachment is comparable to an indictment, and is done by the U.S. House of Representatives.
If the House votes for impeachment, the Senate holds a trial, with the Chief Justice of the United States presiding, to determine whether the person shall be convicted and removed from office.
Two-thirds of the members present must vote to convict.
Former President Bill Clinton was impeached by the House but was not convicted by the Senate.
http://www.constitutionproject.org/ci/newsroom_guide/29.htm
But since we're talking about the impeachment of SC judges, shouldn't the CJ have to recuse himself as too close to the "defendant"? Who presides if it's the CJ himself that's being impeached?