DENVER (KDVR) — The new Colorado gun law that limits sales to people age 21 and older is on hold.

A federal judge ruled Monday in favor of a gun advocacy group, which asked the court to block the law. Senate Bill 23-169 took effect Monday, but the judge’s ruling blocks the state from enforcing it until the case is heard in court.

Rocky Mountain Gun Owners argues the law is a Second Amendment violation.

“Since the day this legislation was introduced, we knew it was unconstitutional,” executive director Taylor Rhodes said in a statement. “Under the Golden Dome, at the unveiling of this proposal, RMGO warned the bill sponsors this would quickly be struck down by a federal judge. Today, our crystal ball became a reality. But it doesn’t stop here. We won’t stop fighting until every single unconstitutional anti-gun law is struck down.”

The group was already suing Democratic Gov. Jared Polis over the law. Named as plaintiffs in the case are two Coloradans, who are older than 18 but younger than 21 and who said they want to buy a gun for self-defense.

The governor’s office issued a statement after the ruling.

“Since 1968, federal law has required Coloradans to be 21 years old to purchase a pistol, but a loophole allowed kids under age 21 to legally buy a rifle instead,” a spokesperson for Polis’ office said. “This law closes that loophole and the governor hopes that the courts agree with him that the law is fully consistent with our Second Amendment rights. The governor is working towards his goal of making Colorado one of the 10 safest states in the country — and the same age requirements for pistols and rifles would help support responsible gun ownership.”

Everyone for Gun Safety also sent a statement to FOX31.

“Legislation to raise the age to purchase a firearm is not only a common-sense measure to curb violence, it’s constitutional,” said Nick Suplina, senior vice president for law and policy at Everytown for Gun Safety. “We remain confident this lifesaving bill will hold up in court, and remain committed to ensuring the full implementation of this legislation.”

Supreme Court decision fuels gun law challenges

Phillip A. Brimmer, chief judge for the U.S. District of Colorado, wrote Monday’s ruling. He said the plaintiffs showed evidence that the law violates their constitutional rights, and blocking the law while the case is heard “is in the public interest.”

The gun group cites the 2022 U.S. Supreme Court decision in New York State Rifle & Pistol Association v. Bruen. In that case, the nation’s high court ruled that Americans have a right to carry guns in public for self-defense. The case also set a standard that courts must look at history to decide the constitutionality of gun laws.

In the state’s opposition filing, Attorney General Phil Weiser said Colorado has used 21 as the default age of majority since 1861. He said other states have long had a similar law on the books and argued the challenge in Colorado is unlikely to succeed.

Still, the judge ruled that the state “has not identified founding era gun laws that are analogous to SB23-169.”

Brimmer said the preliminary injunction will stay in effect until a decision is made on the law’s merits. No hearing date had been set as of Monday afternoon.