Three years ago, a federal ban on "bump-stock-type devices" took effect, transforming otherwise law-abiding owners of such firearm accessories into felons overnight.
Despite its severe and startling consequences, that ban was never approved by Congress. It was unilaterally imposed by the Trump administration, which expanded the statutory definition of "machinegun" to include bump stocks and rifles equipped with them.
As the Firearms Policy Coalition (FPC) explains in a brief it recently filed with the U.S. Court of Appeals for the 5th Circuit, that redefinition "defies any recognizable public meaning of the language of the statute and leads to absurd results."