SPRINGFIELD, Ill. — The Illinois Supreme Court on Friday upheld the state's ban of the type of semiautomatic weapons used in hundreds of mass killings nationally.

 In a 4-3 decision Friday, the high court found that the Protect Our Communities Act does not violate the federal Constitution’s guarantee of equal protection of the law nor the state constitution’s bar on special legislation.

The lawsuit, filed by Republican Rep. Dan Caulkins, of Decatur, and like-minded gun-owners, alleges the law violates the Second Amendment right to keep and bear arms. But it also claims the law is applied unequally.

The law bans dozens of specific brands or types of rifles and handguns, .50-caliber guns, attachments and rapid-firing devices. No rifle is allowed to accommodate more than 10 rounds, with a 15-round limit for handguns. The most popular gun targeted is the AR-15 rifle.

Democratic Gov. J.B. Pritzker signed the Protect Our Communities Act hours after lawmakers sent it to him in a lame-duck session in January, months after a shooter using a high-powered rifle killed seven and injured dozens on Independence Day 2022 in the Chicago suburb of Highland Park. The new law set off a firestorm of criticism from gun-rights advocates, including angry county sheriffs who were nearly unanimous in signing a statement that they would not zealously enforce the law.

Bolstered by the 2022 U.S. Supreme Court case that determined Americans have a right to carry weapons in public for self-defense, Caulkins and other gun owners said the semiautomatic ban clearly violates the right to possess guns. But they also claimed it violates the Constitution's right to equal protection of the law and a state constitution provision banning “special legislation” when a “general law is applicable.” A lower court agreed in March.

The lawsuit alleged the law was unequally applied because anyone who had a semiautomatic weapon on the date the law took effect could keep it, although they're restricted in selling or transferring such weapons. They must register their guns with the Illinois State Police by Jan. 1, 2024.

The ban also exempts law enforcement officers, including those retired, and on-duty military. Critics argued many civilians have more experience and training in handling semiautomatic weapons than law enforcement officers.

“We hold the circuit court erroneously entered summary judgment for plaintiffs on their equal protection and special legislation claims. Plaintiffs are not similarly situated to the trained professionals. To the extent plaintiffs claim they possess restricted items, they are not treated differently from the grandfathered individuals. To the extent plaintiffs claim they do not possess restricted items, they are dissimilar to the grandfathered individuals, who have a reliance interest in retaining them,” the court’s majority wrote.

“Second, we hold that plaintiffs waived any second amendment challenge to the restrictions, as the complaint did not state a claim and plaintiffs explicitly and repeatedly disclaimed any such argument in the circuit court. Third, we hold plaintiffs’ failure to cross-appeal from the denial ofrelief under count II bars them from renewing their three-readings claim here. For these reasons, the judgment of the circuit court of Macon County is reversed."

Democrats, who control all levers of the state's legislative and executive branch, also have a 5-2 majority on the state Supreme Court. Pritzker applauded the decision Friday.

This is a commonsense gun reform law to keep mass-killing machines off of our streets and out of our schools, malls, parks, and places of worship. Illinoisans deserve to feel safe in every corner of our state—whether they are attending a Fourth of July Parade or heading to work—and that’s precisely what the Protect Illinois Communities Act accomplishes. This decision is a win for advocates, survivors, and families alike because it preserves this nation-leading legislation to combat gun violence and save countless lives,” he said. 

Several other lawsuits against the ban filed in federal court were consolidated and are awaiting action in an appeals court.

Illinois State Sen. Jason Plummer, R-Staunton, who represents parts of St. Clair and Madison County, reacted to the decision on social media.

"The IL Supreme Court was trying to thread a needle it seems. They stood by their political patrons but don't want to overruled by the fed case. It's up to fed court...let's pray they put the Constitution over petty politics," he wrote.