Colorado Gov. Jared Polis signed into law a major gun control bill on Thursday, the culmination of months of bitter legislative debate, 11th-hour concessions and pressure campaigns. 

Beginning in August 2026, Coloradans will need to apply for a permit and undergo hours of vetting and training to purchase certain semiautomatic guns, including AK- and AR-style rifles and pistols. 

“I really think this bill will make Colorado communities safer and prevent both accidents as well as reduce gun violence,” Polis said during the bill signing, “and ultimately that means saving lives while protecting our 2nd Amendment rights and, of course, upholding Colorado’s proud tradition of sports shooting and hunting.” 

The measure, Senate Bill 3, was led by Sen. Tom Sullivan, D-Centennial, whose son, Alex, was murdered in the 2012 Aurora movie theater shooting. 

“My family made the decision that we would not be silent or indivisible,” Sullivan said. “We would speak out and be present for all those who have been impacted by the public health crisis that is gun violence like we have.” 

Statehouse Democrats have been trying for three years to pass legislation that targets semiautomatic guns after two previous attempts failed. 

Originally, Senate Bill 3 would have outright banned the sale and manufacture of firearms that accept detachable ammunition magazines. But to assuage concerns from Polis and a handful of leery Democrats, bill sponsors agreed to a carveout that allows otherwise prohibited guns to still be purchased. 

Under the measure, would-be purchasers would need to pass a background check and undergo up to 12 hours of state-mandated safety training offered through a local sheriff’s office and administered by a qualified firearms instructor. 

The course would cover topics like safe gun use, federal and state firearm laws and de-escalation and crisis intervention tactics. Applicants would need to score 90% or higher on a test at the end of the course to be approved for a semiautomatic gun purchase. They would also need to renew their training every five years to make future purchases.

Other changes included expanding eligibility for who can inherit a gun based on a gun owner’s will and exempting commonly used hunting rifles from the bill. 

Senate Bill 3 narrowly passed the Senate in a 19-15 vote in February and was approved by the House in March in a 36-28 vote.

Republicans remained uniformly opposed to the measure, which they labeled an affront to constitutional rights. They also raised concern with the administrative burden it would place on sheriff’s offices and criticized the bill’s price tag at a time when the state is facing a major budget deficit. 

An analysis by the nonpartisan Legislative Council Staff found the bill would cost the state roughly $1.4 million next fiscal year to establish the permitting program. 

The money, however, would come from the Parks and Outdoor Recreation Cash Fund rather than the general fund, which is the source of the state’s budget pressures and the target of cuts. The permitting program is also expected to generate and grow its own revenue in future years through the sale of permits.

While a handful of Democrats joined Republicans in opposing Senate Bill 3, some more moderate Democrats on the Western Slope ultimately supported the bill after it was amended to include the training exemption. 

“It sets up a process where there won’t be an arbitrary ban that would have hurt hunters and caused 2nd Amendment legal challenges but creates more safety training that will save lives,” said Sen. Dylan Roberts, D-Frisco, prior to voting for the bill’s amended version in the Senate. 

Rep. Meghan Lukens, D-Steamboat Springs, who had voted against a more sweeping “assault weapons” ban last session, supported Senate Bill 3, which she called a compromise “to protect law-abiding gun owners while requiring training before someone can purchase the most lethal weapons on the market.”

Gun advocates had been pressuring Polis to veto the bill, with the group Rocky Mountain Gun Owners delivering thousands of petitions to the governor’s office urging him to block the legislation. The group has vowed to work to unseat Democrats in more moderate districts who voted for the bill in the 2026 General Election. 

Along with Senate Bill 3, Polis also signed Senate Bill 59, which directs the Colorado Department of Public Safety to apply for federal grant funding associated with the state’s response to mass shootings. The bill was also sponsored by Sullivan.