FILE - In this July 20, 2014 photo, with guns displayed for sale behind her, a gun store employee helps a customer at Dragonman's, east of Colorado Springs, Colo. (AP Photo/Brennan Linsley, File)

DENVER (AP) — A Colorado proposal requiring a criminal background check and safety course for people who want to buy semiautomatic guns with detachable magazines passed the state Senate on Tuesday, clearing a major legislative hurdle in a state that’s experienced some of the worst mass shootings in the U.S.

If passed, Colorado would join roughly a dozen other states that require some kind of safety training or exam to purchase a firearm.

Colorado Democrats’ yearslong campaign to ban semiautomatic firearms, in line with other blue states such as California and New York, has been framed by the mass killings at Columbine High School in 1999, the movie theater in Aurora, Colorado, in 2012 and the LGBTQ+ nightclub in Colorado Springs in 2022.

But those past attempts floundered under the state's streak of libertarianism, including in its Democratic governor, Jared Polis, even as the party seized and held large majorities in the statehouse.

When first introduced, the bill banned the sale and manufacture of several types of guns made with detachable magazines, including semiautomatics and some shotguns and pistols. Proponents argued that allowing only permanently attached magazines would limit the damage a would-be shooter could cause by forcing them to reload bullet-by-bullet.

But in a concession to Polis and some wary lawmakers in their own party, the bill was further watered down last week, allowing people to purchase guns with detachable magazines if they pass a background check and state-sanctioned safety course. This version of the bill now goes to the House, which is expected to pass it, and is more likely to get the governor's approval.

One of the bill's sponsors is Democratic state Sen. Tom Sullivan, whose son was killed in the Aurora movie theater shooting.

“This is the high-capacity magazine that my son’s killer brought into the movie theater,” Sullivan said as he thrust a photo toward Senate Republicans during the chamber's first floor debate on the bill last week. “When this magazine jammed after 72 shots, the dying stopped.”

Republicans have decried the proposal as a severe violation of Second Amendment rights and framed it as an effective ban on the weapons. Their arguments pushed last week's debate into the wee hours of the morning.

“The founders recognized that self-defense is a fundamental, natural right that predates government itself," said Republican Sen. Paul Lundeen, the chamber's minority leader, before the vote Tuesday. "The burden is on the government to justify restrictions, not on you to prove eligibility.”

A slew of caveats exempts different classes of firearms from the restrictions, including common hunting rifles and certain guns that fire .22 or lower caliber ammunition. The bill would allow those who already have the affected guns to keep them.

___

Bedayn is a corps member for the Associated Press/Report for America Statehouse News Initiative. Report for America is a nonprofit national service program that places journalists in local newsrooms to report on undercovered issues.

News from © The Associated Press, 2025