In a brief order, a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit said the lower court judge had made “insufficient findings and conclusions” in blocking the execution of Keith Nelson, which is due to take place on Friday.

“The ruling basically allows the government to pick and choose when it will follow the law,” said Dale Baich, one of Nelson’s lawyers.

A Bureau of Prisons spokeswoman said the execution is “currently proceeding as scheduled.”

“Where the government argues that a lethal injection drug is legally and constitutionally permissible because it will ensure a ‘humane’ death, it cannot then disclaim a responsibility to comply with federal statutes enacted to ensure that the drugs operate humanely,” Chutkan wrote in a 13-page opinion.

Prior to July, there had been only three federal executions since 1963, all between 2001 and 2003, all using sodium thiopental. As supplies of that drug vanished, Texas, Missouri and other states that use capital punishment switched to pentobarbital and the Justice Department announced last year it would follow suit.