In December, the administration issued a ban on the devices, which effectively turn semi-automatic rifles into machine guns, following the deadliest mass shooting in U.S. history in Las Vegas on October 1, 2017. The prohibition is due to come into effect in a month’s time, by which time bump stock owners are supposed to have given them up or destroyed them.

Immediately after the Trump administration announced the ban, a challenge appeared from the Firearms Policy Coalition, the Firearms Policy Foundation, and the Madison Society Foundation, which claimed the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and then-acting U.S. Attorney General Matthew Whitaker had overstepped their authority.

It was more of a procedural challenge than a Second Amendment invocation, based on the fact that the ATF once maintained only certain bump stocks should be illegal, but changed its stance at the president’s urging.

U.S. District Judge Dabney L. Friedrich rejected the attempt in a 64-page decision late Monday. Friedrich, a Trump appointee, said it was “reasonable” of the ATF to decide, as it did, that a bump stock does what a machine-gun does. Machine-guns are illegal under federal law, so bump stocks can also be banned.

“That this decision marked a reversal of ATF’s previous interpretation [of the meaning of bump stock] is not a basis for invalidating the rule, because ATF’s current interpretation is lawful and ATF adequately explained the change in interpretation,” the judge said.

Friedrich also rejected the plaintiffs’ argument that Trump had unconstitutionally appointed Whitaker.