The Supreme Court struck down the federal ban on bump stocks on Friday, legalizing a device that can effectively transform semiautomatic rifles into machine guns. Predictably, the court split 6–3, with the Republican-appointed justices carving a massive loophole in federal law at the behest of the firearms industry. Justice Clarence Thomas’ majority opinion is rooted in historical misrepresentations and utterly implausible manipulations of the statutory text. It enables future mass shooters to equip their AR-15s with an attachment that increases the rate of fire exponentially, to up to 800 rounds per minute.

Dahlia Lithwick and Mark Joseph Stern discussed the decision on Saturday’s episode of Amicus. They were joined by David Pucino, an expert in firearms law and legal director of the Giffords Law Center. Their conversation has been edited for length and clarity.

Dahlia Lithwick: Justice Thomas makes the claim that the Bureau of Alcohol, Tobacco, and Firearms did a complete 180 on how it viewed bump stocks, suddenly changing their minds after the Las Vegas massacre and deciding that, actually, they are machine guns. That’s just not true, right?

Mark Joseph Stern: This idea that ATF said bump stocks were 100 percent legal, then turned around in response to political pressure and said they were unlawful all along—that’s a misrepresentation of history. What really happened was that gunmakers were developing various tools to help make semiautomatic rifles fire at a higher rate. ATF looked at these and said some were potentially legal while others were not, on a case-by-case basis, without making a formal determination at the agency level. Some were snuck through under false pretenses as an accommodation for disability. And when ATF decided to take a holistic look at this issue after the Las Vegas shooting, it decided that, when bump stocks operate a certain way—basically, enabling automatic fire—they are illegal.

That, to me,........

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