The Supreme Court has struck down the reclassification of bump stocks that was promulgated by the Trump administration back in 2018. As I noted earlier this year, this was not a Second Amendment case, but a statutory case, and, as such, the question was not whether bump stocks count as “arms,” but whether the National Firearms Act of 1934 grants the executive branch the power to regulate them in the same manner as it regulates machine guns. As the Court makes clear, the answer to this is unquestionably no. In consequence, the regulation must fall.

That bump stocks do not count under the NFA is not a new finding. Indeed, as the majority opinion notes in its introduction:

The question in this case is whether a bump stock transforms a semiautomatic rifle into a “machinegun,” as defined by §5845(b). For many years, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) took the position that semiautomatic rifles equipped with bump stocks were not machineguns under the statute. On more than 10 separate occasions over several administrations, ATF consistently concluded that rifles equipped with bump stocks cannot “automatically” fire more than one shot “by a single function of the trigger.” See App. 16–68. In April 2017, for example, ATF explained that a rifle equipped with a bump stock does not “operat[e] automatically” because “forward pressure must be applied with the support hand to the forward handguard.” Id., at 66. And, because the shooter slides the rifle forward in the stock “to fire each shot, each succeeding shot fir[es] with a single trigger function.” Id., at 67.