The Supreme Court has refused to delay a court order for California to release nearly 10,000 inmates by year's end to improve conditions in state prisons.
The court voted 6-3 Friday to reject a plea from Gov. Jerry Brown. Brown argued the early release would jeopardize public safety.
Justices Samuel Alito, Antonin Scalia and Clarence Thomas said they would have granted the state's request.
The court ruled 5-4 in 2011 that the state must cut its inmate population to deal with unconstitutional prison conditions caused by overcrowding.
State officials said conditions have improved dramatically since a lower court order in 2009.