Attorney General William Barrhas directed the Federal Bureau of Prisons to resume capital punishment, nearly two decades after the death penalty was last used at the federal level.

Barr has also directed the acting director of the BOP, Hugh Hurwitz, to schedule the executions of five death row inmates beginning this December.

Executions had lapsed due to a shortage of sodium thiopental, an anesthetic that’s part of a three-drug cocktail used in executions as stipulated by the Federal Execution Protocol.

Barr directed the BOP on Thursday to adopt an addendum to the protocol, replacing the three-drug procedure with a single drug — pentobarbital.

Single doses of pentobarbital have been used before at the state level, where sodium thiopental shortages have prompted potentially unconstitutional workarounds.

In 2014, then-President Barack Obama ordered a review of the lethal injection drugs that states had begun to use instead of sodium thiopental, following a horrific, botched execution in Oklahoma.

That following year, Oklahoma legalized execution by nitrogen asphyxiation, and also authorized the use of either electrocution or the firing squad in the event traditional drugs are unavailable.

“Congress has expressly authorized the death penalty through legislation adopted by the people’s representatives in both houses of Congress and signed by the President,” Barr said in a statement. “Under Administrations of both parties, the Department of Justice has sought the death penalty against the worst criminals, including these five murderers, each of whom was convicted by a jury of his peers after a full and fair proceeding.

“The Justice Department upholds the rule of law—and we owe it to the victims and their families to carry forward the sentence imposed by our justice system,” he added.

The last execution under the federal death penalty took place on March 18, 2003, according to data from the Death Penalty Information Center. Sixty two inmates are currently on federal death row.