The U.S. Supreme Court could announce as early as Tuesday whether it will hear a challenge to a suburban Chicago law banning firearms commonly known as assault weapons.
If the court agrees to hear the case, it would cast a shadow over similar bans in seven states. But declining to take it up would boost efforts to impose such bans elsewhere, at a time of renewed interest in gun regulation after recent mass shootings.
Gun rights advocates are challenging a 2013 law passed in Highland Park, Illinois, that bans the sale, purchase, or possession of semi-automatic weapons that can hold more than 10 rounds in a single ammunition clip or magazine. In passing the law, city officials cited the 2012 shootings at Sandy Hook Elementary School in Connecticut and a movie theater in Aurora, Colorado.
The ban also lists certain specific rifles, including those resembling the AR-15 and AK-47 assault-style firearms.
Semi-automatic weapons are capable of shooting a single round with each pull of the trigger and, consequently, can fire rapidly. Large capacity magazines reduce the need to reload as often.
A federal district judge upheld the law, and so did a federal appeals court panel by a 2-1 vote.
Central to the dispute is the Supreme Court's 2008 ruling that, for the first time, said the Constitution's Second Amendment provides an individual right to own a handgun for self-defense.
While it was a watershed ruling for gun rights, it also said "dangerous and unusual weapons" can be restricted.
The firearms banned by the Highland Park ordinance may be common, the appeals court said. But it added that "assault weapons with large-capacity magazines can fire more shots, faster, and thus can be more dangerous in the aggregate. Why else are they the weapons of choice in mass shootings?"
The opinion, written by Judge Frank Easterbrook, a Ronald Reagan appointee, said that "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."
The Illinois State Rifle Association, which is challenging the law's constitutionality, says the weapons are in no way unusual. The AR-15, the group says, is the best-selling rifle type in the nation.
Between 1990 and 2012, the group says, more than 5 million AR-type rifles were manufactured for sale in the U.S., and 3.4 million more were imported. As for the magazines, the gun rights group says they are "ubiquitous," with nearly 75 million of them in possession of gun owners.
In a friend of court brief urging the Supreme Court to take the case, lawyers for 24 states say the weapons banned by the Highland Park ordinance are not only commonly used, but are also protected by state laws that forbid local communities to restrict them.
A ruling striking down the city ordinance would undercut similar bans in California, Connecticut, Hawaii, New York, Maryland, Massachusetts, and New Jersey, and in Chicago and surrounding cities.
This story originally appeared on NBCNews.com