The Supreme Court could hand down a decision any day now in National Association for Gun Rights v. City of Naperville, a case that could legalize assault weapons and high-capacity magazines in all 50 states.

The case challenges a Naperville, Illinois, ordinance and a similar Illinois state law, both of which ban assault weapons, which the state law defines to include certain semiautomatic rifles such as AR-15s and AK-47s. Additionally, the state law prohibits the sale of a “large capacity ammunition feeding device,” which the statute defines as long gun magazines that hold more than 10 rounds of ammunition, or handgun magazines that hold more than 15 bullets.

The plaintiffs, which include a gun shop owner and a gun rights group, claim the two statutes violate the Second Amendment.

Should the Supreme Court accept that argument and overturn these laws, it would have sweeping implications for the entire country. That decision would need to be followed throughout the entire nation — which would most likely mean that neither any state nor the US Congress could ban assault rifles or high-capacity magazines.

And there is good reason to fear that this Court could, at the very least, decide to make semiautomatic assault rifles legal throughout the United States. In 2011, a federal appeals court upheld the District of Columbia’s ban on assault weapons — over the dissent of an up-and-coming right-wing judge named Brett Kavanaugh.