Justice Clarence Thomas once opposed Highland Park's ban on military-style rifles, saying the 'overwhelming majority' of those with the guns use them lawfully

• Highland Park, Illinois, banned military-style rifles nearly a decade before Monday's mass shooting.
• The ban was challenged, and the case made its way to the Supreme Court, which refused to hear it.

Nearly a decade before Monday's deadly mass shooting at a Fourth of July parade in Highland Park, Illinois, that left seven dead and dozens injured, the Chicago suburb banned "assault weapons," including AR‐15- and AK‐47-style firearms.

That 2013 ban was swiftly challenged, and the case made it all the way to the US Supreme Court, which rejected to hear it and instead let a lower court's ruling in favor of the ordinance stand.

At the time, Justice Clarence Thomas, a conservative who joined the nation's highest court in 1991, opposed Highland Park's prohibition on military-style rifles and large-capacity magazines, writing in a dissent that the "overwhelming majority" who used such weapons used them lawfully.

In Thomas' dissent, which was filed in December 2015 and joined by Justice Antonin Scalia, he made references to the Second Amendment.

"The ordinance criminalizes modern sporting rifles (e.g., AR-style semi automatic rifles), which many Americans own for lawful purposes like self-defense, hunting, and target shooting," the dissent said.

Thomas deemed the city's ban "highly suspect because it broadly prohibits common semiautomatic firearms used for lawful purposes."

"Roughly five million Americans own AR-style semiautomatic rifles," the dissent said, adding: "The overwhelming majority of citizens who own and use such rifles do so for lawful purposes, including self-defense and target shooting."

The US Court of Appeals for the Seventh Circuit upheld Highland Park's ban on military-style rifles after a local doctor and the Illinois State Rifle Association sued the city over it.

"Assault weapons with large‐capacity magazines can fire more shots, faster, and thus can be more dangerous in aggregate. Why else are they the weapons of choice in mass shootings?" the appellate court wrote in its April 2015 opinion.

The court added: "A ban on assault weapons and large‐capacity magazines might not prevent shootings in Highland Park (where they are already rare), but it may reduce the carnage if a mass shooting occurs."

Authorities recovered a "high-powered rifle" from the scene after Monday's mass shooting in Highland Park, which came on the heels of massacres in Uvalde, Texas, and Buffalo, New York.

It was not immediately clear where the gun came from — but Democratic Mayor Nancy Rotering of Highland Park, who signed the ordinance banning military-style rifles in 2013 — said the gun used in the shooting was "legally obtained."

A suspect in the shooting was taken into custody on Monday after an hours-long manhunt, the FBI said.

Authorities believe that the shooting suspect used a weapon "similar" to an AR-15 and "pre-planned the attack for several weeks," Lake County Major Crime Task Force spokesman Christopher Covelli said during a press briefing on Tuesday.

Police confirmed the weapon was legally purchased in the Chicago area.