Federal law strips the right to keep and bear arms from anyone convicted of a felony—for life—regardless of the offense. It does so on the strength of the felony label alone.

Petitioner Joseph Johnson’s case shows what that rule means in practice. His only felony—a 2015 conviction for cultivating marijuana—occurred eight years before, and a state away from, his firearm charge, and nothing connected the two. His sentence for that offense shows how minor it was: he received probation, not prison, and the probation even ended early. Regardless, Mr. Johnson must now endure lifetime disarmament and a subsequent criminal conviction—not because he is dangerous, but because of his status as a felon.

Mr. Johnson is asking the Supreme Court to review the constitutionality of categorical felon disarmament. Cato filed an amicus brief supporting his petition. Mr. Johnson remains part of “the people” protected by the Second Amendment. The right to keep and bear arms is an individual right, not a civic right, and felons can be disarmed only in a manner consistent with the nation’s historical tradition of firearm regulation.

Founding-era laws disarmed people because they were dangerous, not because of virtue-based status. And the Supreme Court’s recent decision in Hemani refused to let the government substitute membership in a statutory category for a judgment about dangerousness. Moreover, the felony label once reserved for the gravest crimes now reaches a vast range of conduct with no connection to violence, and legislatures can expand it at will. Treating that label as a proxy for danger would let lawmakers shrink the Second Amendment’s guarantee simply by writing new felonies, a power to which no other enumerated right is subject.

Even if the government could supply a historical reason for disarming nonviolent felons, the law Mr. Johnson challenges would still fail because of how it disarms them. Historically, disarmament followed a judicial finding that the person was dangerous, and it was temporary. A felony conviction provides process, but on the wrong question. The mere fact of a felony conviction establishes nothing about whether a person poses a threat. Regardless, federal law imposes its lifelong prohibition without a finding of danger.

The government bears the burden of proving that gun-control laws are consistent with history and tradition. In cases like this one, it cannot carry that burden, and the rule applied below never even makes it try. Mr. Johnson and other nonviolent felons like him should not be consigned to lifetime disarmament simply because courts excused the government from a burden it could never have met.