The US Supreme Court upheld a Democratic-backed ban on assault-style rifles and large-capacity magazines enacted in Illinois.Scott Olson/Getty Images

The US Supreme Court will not halt a new Illinois law prohibiting the sale of certain semi-automatic firearms and high-capacity magazines.

On Wednesday, the Supreme Court denied an emergency request from those challenging the law prohibiting assault weapons.

Illinois Assault Weapons Ban

Opponents of the legislation had urged the court to suspend the law pending the outcome of an ongoing legal challenge. The court did not comment, and no judge publicly dissented.

Justice Amy Coney Barrett ruled on Wednesday, a day after the Illinois Supreme Court heard a separate challenge to the state's assault weapons ban. The justices are considering placing the legislation on pause temporarily. The court's arguments centered on equal protection rights, as per CBS News.

Hundreds of mothers gathered in Springfield to advocate for gun safety legislation. Fifty percent of the mothers were from Chicago. They boarded a bus at Union Station to meet hundreds of other mothers in Springfield.

The organization wants the state legislature to approve legislation mandating safe gun storage, prohibiting domestic violence offenders from possessing firearms, and holding the gun industry accountable. In the meantime, a federal appeals court reinstated the Illinois assault weapons ban earlier this month after a federal magistrate in the state had halted the law.

The decision, contained in a brief, unsigned order, means that the Illinois law enacted in response to a shooting that killed seven people on July 4, 2017, in Highland Park will remain in effect while legal challenges continue. A federal magistrate halted the law in a separate case, but the 7th US Circuit Court of Appeals has stayed that decision. In January, according to NBC News, the Supreme Court declined to halt new gun restrictions in New York.

Illinois Gov. Pritzker Hails Supreme Court's Decision

The combined effect of the two decisions indicates that the justices are willing to give lower courts time to contemplate the impact of last summer's Supreme Court decision that dramatically expanded firearms rights under the Second Amendment.

Additionally, the appeals court expedited the review of five cases challenging the new law. The Supreme Court of Illinois is contemplating an analogous case. Due to the Supreme Court's decision, a Naperville, Illinois, ordinance that bans assault-style weapons will also remain in effect.

In January, Democratic Illinois Governor J.B. Pritzker signed into law the Protect Illinois Communities Act, which prohibits the sale and distribution of numerous types of high-powered semi-automatic "assault weapons," including AK-47 and AR-15 rifles and magazines that hold more than 10 rounds for long guns and 15 rounds for handguns.

Pritzker applauded the action of the Supreme Court. Existing proprietors are exempt and have until January 1, 2024, to register assault weapons with state police, as per Reuters. Last June, the Supreme Court issued a landmark decision recognizing the right to carry a handgun for self-defense in public. According to Brown, subordinate courts have ignored this decision.

In signing the bill, Pritzker also referenced other recent mass shootings, which are a common occurrence in the United States, including an attack in 2022 that killed 19 children and two teachers at an elementary school in Uvalde, Texas, and a shooting in 2012 that killed 20 children and six adults at Sandy Hook Elementary School in Newtown, Connecticut.