Supreme Court

Clarence Thomas Explains Why the Commerce Clause Cannot Justify Federal Bans on Gun Possession

Even under the Supreme Court's highly elastic understanding of that clause, Thomas says, such laws do not qualify as regulation of interstate commerce.

Jacob Sullum | 6.23.2026 3:50 PM

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Last week in United States v. Hemani, the Supreme Court unanimously ruled that the government may not strip people of their Second Amendment rights or prosecute them for illegal gun possession simply because they are marijuana users. Justice Clarence Thomas, the longest-serving current member of the Court, joined his colleagues in upholding the Second Amendment rights of cannabis consumers threatened with prosecution under 18 USC 922(g)(3), which makes it a felony for an "unlawful user" of "any controlled substance" to possess a firearm. But Thomas perceived another constitutional problem with that law, arguing that it exceeds the federal government's power to regulate interstate commerce.

As Reason's Damon Root notes, Thomas' understanding of the Commerce Clause underlies a "lonely crusade" that he has been waging for decades. But the fact that Thomas has not mustered much support for his position from his colleagues does not mean he is wrong. To the contrary, it is hard to deny that laws like Section 922(g)(3), which applies to gun possession "in or affecting commerce," rely on a highly elastic interpretation of the Commerce Clause that converts it into a license for nearly anything Congress wants to do.

Thomas' objection to Section 922(g)(3) also applies to other provisions of the same law that categorically prohibit gun possession by broad classes of Americans. Those provisions include Section 922(g)(1), which permanently disarms people who have been convicted of crimes punishable by more than a year of incarceration, and Section 922(g)(4), which covers people who have been subjected to involuntary psychiatric treatment. In fact, all of the categorical bans in Section 922(g) rely on the same dubious justification, purporting to establish congressional authority by criminalizing gun possession "in or affecting commerce."

In practice, that supposed qualification does not impose any limits at all. Thomas illustrates that point by noting what would have been required to convict the Texas cannabis consumer whose prosecution the Supreme Court barred in Hemani. In addition to establishing that Ali Hemani owned a pistol and used marijuana a few times a week (both of which he admitted), prosecutors would have had to prove that his gun "had previously traveled in interstate commerce."

Since Hemani owned a Glock 19 pistol manufactured either in Austria or Georgia, that requirement would have been easily met. Prosecutors "alleged only that the firearm that he possessed........

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