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.

What changed? This:

ATF abruptly reversed course in response to a mass shooting in Las Vegas, Nevada. In October 2017, a gunman fired on a crowd attending an outdoor music festival in Las Vegas, killing 58 people and wounding over 500 more. The gunman equipped his weapons with bump stocks, which allowed him to fire hundreds of rounds in a matter of minutes. This tragedy created tremendous political pressure to outlaw bump stocks nationwide.

But that pressure was real. But it was not law. The United States Constitution is extremely clear on how laws are made, and “a lot of people are upset about something” lies nowhere within its instructions. If one wishes, one can argue that Congress ought to have changed the law after the Nevada massacre. But it didn’t. And, because it didn’t, the executive branch had no more authority to issue its rule than it had had on the “more than 10 separate occasions over several administrations” on which it had concluded that such a change would be ultra vires.

In her dissent, Justice Sotomayor contends that none of this matters. “When I see a bird that walks like a duck, swims like a duck, and quacks like a duck,” she says, “I call that bird a duck.” Within the context of statutory interpretation, I’m afraid that I do not know what this means. The question at hand was not whether bump stocks make semi-automatic firearms look like automatic firearms; the question was whether bump stocks physically transform semi-automatic firearms into firearms that, per the relevant language within the law, are able to shoot repeatedly “by a single function of the trigger.” Obviously, they don’t. Perhaps Sotomayor believes that the language Congress passed is too vague. Perhaps, instead, she’d like 26 U. S. C. §5845(b) to discuss effect or implication or to lay out some vague sense of congressional purpose that could be broadly applied by the other branches. If so, that is her prerogative, but, until it does, her job is to uphold the law as it is written, and, in this case, it was the six colleagues whom she criticizes who did that.