While Attorney Jeff Sessions is waging war on opioids, the Nevada Department of Corrections has secured fentanyl — a powerful opioid at the center of the crisis — to use in an upcoming execution.

Fentanyl will be used as part of a three-drug cocktail in addition to diazepam, which causes unconsciousness, and cisatracurium, which causes paralysis. This cocktail has never been used in an execution, and experts are concerned about its effectiveness.

“Use of these drugs could result in a botched execution, leading to torture or a lingering death in violation of the protections of the United States Constitution,” ACLU of Nevada Executive Director Tod Story said in a statement.

The ACLU of Nevada is currently looking at what legal avenues it can take to challenge the untried procedure.

Scott Dozier, 46, is set to be executed on Nov. 14 for two murders in the early 2000s. In 2002 Dozier shot and dismembered 22-year-old Jeremiah Miller. At the time of his trial he was already serving a 22-year sentence for the drug-related murder of Jasen Green.

Dozier’s execution will be Nevada’s first in more than a decade, and it will take place in the state’s new execution chamber, renovated last year for nearly $900,000.

Dozier said he wants to be executed, vowing to withdraw any appeal. His lawyer could not be reached for comment Wednesday.

A lot is still unknown about Nevada’s execution plan as the scheduled lethal injection approaches, including the order in which the drugs will be administered.

Susi Vassallo, a New York University professor of emergency medicine, told The Marshall Project that the three-drug protocol “doesn’t make much sense.”

“You don’t need Valium [aka diazepam] if you have fentanyl,” she said, adding that both drugs are lethal and cause unconsciousness. Vassallo said that fentanyl would need to be administered in a large, ongoing dose in order to kill the inmate, a departure from past lethal injection protocols.

The Nevada Department of Corrections did not respond for a request for comment regarding the order in which the drugs will be used.

The Nevada Legislature considered abolishing the death penalty earlier this year, but the bill failed after a heated committee hearing in March. State Sen. Tick Segerblom, a sponsor of the bill and a death penalty opponent, is concerned about the state’s plan to use fentanyl.