A federal judge in Colorado on Monday temporarily blocked a state law that raised the legal age requirement for purchasing a firearm to 21.

Chief U.S. District Judge Phillip A. Brimmer ruled in favor of the gun rights group, Rocky Mountain Gun Owners, who had filed a lawsuit against Gov. Jared Polis. 

The state law, SB23-169, was one of several sweeping gun reform measures approved by the state legislature and signed by Gov. Polis in the spring. It sought to prohibit people under the age of 21 from purchasing a gun, with exceptions for active members of the U.S. armed forces, peace officers, and people certified by the Peace Officer Standards and Training board. 

RMGO argued in their lawsuit that law was unconstitutional. The group said if people are allowed to vote when they turn 18, they should be allowed to purchase a gun. 

ARMED WOMAN SHOOTS ROAD RAGE ‘AGGRESSOR’ TRYING TO FORCE HIS WAY INTO HER CAR: DA

Jared Polis speaking with American flags in the background

Gov. Jared Polis explains about his supplemental budget at Carriage House of Governors Mansion in Denver, Colorado on Thursday, January 3, 2023.  (Hyoung Chang/The Denver Post)

"Since the day this legislation was introduced, we knew it was unconstitutional," said RMGO executive director Taylor Rhodes in a written 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." 

DEMOCRATS DEMAND 1,000% EXCISE TAX ON ‘ASSUALT WEAPONS,’ HIGH-CAPACITY MAGAZINES

A spokesman for Gov. Polis’ office said federal law has for more than half a century required Coloradans to be 21 years old to purchase a pistol, but a loophole allowed kids under 21 to legally buy a rifle instead. 

"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 spokesperson said. 

CLICK HERE TO GET THE FOX NEWS APP

"The Governor is working towards his goal of making Colorado one of the ten safest states in the country – and the same age requirements for pistols and rifles would help support responsible gun ownership."