The Justice Department’s effort to ban bump stocks is invalid because President Donald Trump’s pick to temporarily lead the agency lacks authority to hold the position, according to a lawsuit filed Dec. 26.

Matthew Whitaker’s Nov. 7 designation as acting attorney general didn’t follow the requirements of federal law and Constitutional provisions governing appointments of top government officials, the Firearms Policy Coalition Inc. says in the lawsuit.

The Sacramento-based center asked the U.S. District Court for the District of Columbia to enjoin the implementation of the bump stock ban because Whitaker advanced it while improperly exercising authority as acting attorney general. Courts may void actions taken by officials who aren’t validly appointed.

Attorney General Jeff Sessions’ departure should have elevated Deputy Attorney General Rod Rosenstein under DOJ succession rules, the organization says. Further, Whitaker can’t hold the top spot because he hasn’t been confirmed by the Senate, according to the complaint.

Thomas C. Goldstein, a lawyer with Goldstein & Russell P.C. in Bethesda, Md., represents the center. This isn’t the first time Goldstein has argued in court filings that Whitaker’s appointment was unlawful. He also filed a Nov. 16 motion to substitute Rosenstein in for Whitaker in a separate case involving the DOJ before the U.S. Supreme Court.

The administration moved to ban bump stocks after they were used in October 2017 by a gunman who shot at a country music concert in Las Vegas, killing 58 people and injuring 851 more. A bump stock is a device that attaches to a gun and makes it fire more rapidly.

The DOJ is among the federal agencies that are shut down until Congress and the president reach an agreement on government spending.

“Due to the lapse in appropriations, messages submitted through this web form may not be returned until funding is restored,” an automated message said Dec. 26 when Bloomberg Law submitted a request for comment.

The case is Firearms Policy Coalition, Inc. v. Whitaker, D.D.C., No. 1:18-cv-03083, complaint filed 12/26/18