The Justice Department says President Bush's appointment of former Alabama attorney general Bill Pryor as a federal judge is constitutional.
The agency says presidents from 1867 to present have appointed federal judges while Congress was not in session.
The Bush administration is defending Pryor's appointment to the Eleventh U.S. Circuit Court of Appeals -- which has been challenged by Massachusetts Senator Edward Kennedy.
Kennedy says the appointment amounts to an end-run on the Senate's right to confirm or reject the president's choices for judgeships.
Pryor was appointed during the President's Day recess in February after his nomination stalled in the Senate.
But Kennedy says allowing an appointment during a short break could open the door for appointments being made on weekends.