There was a ban on assault rifles in Highland Park.
The Supreme Court refused to hear the case since it was challenged.
Clarence Thomas wrote that an "overwhelming majority" of people use such weapons legally.
The Chicago suburb of Highland Park banned assault rifles like the one used in the Fourth of July parade that left six people dead.
The case made it all the way to the US Supreme Court, which turned down to hear the case and let the lower court's ruling stand.
Conservative Justice Clarence Thomas, who joined the nation's highest court in 1991, dissented from Highland Park's ban on assault weapons.
He called assault weapons "modern sporting rifles" and made references to the Second Amendment.
Modern sporting rifles, which many Americans own for lawful purposes like self-defense, hunting, and target shooting, have been criminalized by the city.
The city's ban on common semiautomatic firearms is highly suspect, according to Thomas.
The majority of citizens who own and use such rifles do so for lawful purposes, including self-defense and target shooting.
Highland Park's assault weapons ban was upheld by the United States Court of Appeals for the Seventh Circuit.
Assault weapons with largecapacity magazines can fire more shots and thus be more dangerous. They are the weapons of choice in mass shootings, according to the appellate court.
If a mass shooting occurs, a ban on assault weapons and large-capacity magazines may reduce the carnage.
On the heels of massacres in Uvalde, Texas, and Buffalo, New York, authorities recovered a high-powered rifle from the scene of the Highland Park shooting.
Nancy Rotering, the Democratic mayor of Highland Park, said that the gun used in the shooting was legal.
The suspect in the shooting was taken into custody by the FBI.
Business Insider has an article on it.