The ruling, handed down Friday by a three-judge panel on the U.S. Court of Appeals for the District of Columbia Circuit, concluded that a lower court judge erred when he vacated Lisa Montgomery's execution date in an order last week.
U.S. District Court Judge Randolph Moss had ruled the Justice Department unlawfully rescheduled Montgomery's execution and he vacated an order from the director of the Bureau of Prisons scheduling her death for Jan. 12.
Montgomery had been scheduled to be put to death at the Federal Correctional Complex in Terre Haute, Indiana, in December, but Moss delayed the execution after her attorneys contracted coronavirus visiting their client and asked him to extend the time to file a clemency petition.
Moss concluded that under his order, the Bureau of Prisons could not even reschedule Montgomery's execution until at least Jan. 1. But the appeals panel disagreed.
Meaghan VerGow, an attorney for Montgomery, said her legal team would ask for the full appeals court to review the case and said Montgomery should not be executed on Jan. 12.
Montgomery was convicted of killing 23-year-old Bobbie Jo Stinnett in the northwest Missouri town of Skidmore in December 2004. She used a rope to strangle Stinnett, who was eight months pregnant, and then cut the baby girl from the womb with a kitchen knife, authorities said.
Montgomery took the child with her and attempted to pass the girl off as her own, prosecutors said.
But her lawyers have argued that their client suffers from serious mental illnesses.
Biden opposes the death penalty and his spokesman, TJ Ducklo, has said he would work to end its use. But Biden has not said whether he will halt federal executions after he takes office Jan. 20.