Gov. Jared Polis signed a sweeping gun-control measure into law Thursday, the culmination of years of effort by advocates and progressive Democrats to limit the sale of high-powered semiautomatic weapons in Colorado.
Starting next summer, Coloradans will have to pass a background check and a training course before they can purchase a swath of semiautomatic firearms that include most of the guns known colloquially as assault weapons. Senate Bill 3 also prohibits the sale of bump stocks and rapid-fire trigger activators, which are firearm components that can increase a gun’s rate of fire.
The bill’s sponsors said it was intended to prevent future mass shootings and enforce the state’s existing prohibition on high-capacity magazines.
“We have been able to add to the safety of each and every Coloradan, especially when it comes to gun violence,” said Sen. Tom Sullivan, a Democrat who co-sponsored the bill with Sen. Julie Gonzales and Reps. Meg Froelich and Andy Boesenecker.
SB-3, which passed the legislature late last month, becomes the most sweeping gun-control measure passed by legislative Democrats in Colorado, and its passage into law was cheered Thursday by national gun-control groups Moms Demand Action and Everytown for Gun Safety.
Although the law doesn’t impose a complete ban on assault weapons or any type of firearm, it follows in the footsteps of previous attempts in the Capitol to fully prohibit the sale or purchase of those guns. A group of activists, including local students who’d repeatedly come to the state Capitol calling for tighter regulations, attended the bill signing in the governor’s office Thursday.
Before the bill was signed, Froelich referred to those students as the “lockdown generation” that has lived their “whole school lives in the shadow of gun violence.”
“Today’s victory is because of the countless students that showed up day after day to testify in support of this life-saving bill,” Grant Cramer, a gun violence survivor and the co-president of Denver East High School’s Students Demand Action chapter, said in a statement. “We refused to take no for an answer and now we’ve strengthened our gun safety laws in Colorado. This is proof that our voices hold power to create change, no matter how big or small.”
Ian Escalante, the executive director of the gun-rights group Rocky Mountain Gun Owners, called the bill’s passage into law “one of the most disgraceful things that’s ever been done in the state.” He said his group was considering legal options to challenge the bill — though they likely won’t be able to pursue litigation until the bill goes into effect next year.
Escalante also said he planned to pursue “electoral accountability” in 2026, referring to challenging Democrats in competitive districts.
“We’re not going to let this law stand,” he said outside the governor’s office, “whether it’s through litigation or whether we kick these (legislative sponsors) out and we replace them with people who will repeal it.”
The new law goes into effect Aug. 1, 2026. It applies primarily to gas-operated semiautomatic firearms that accept detachable magazines, a definition that includes the AR-15 rifle and many guns like it. It would require people pass background checks from their county sheriff. Should they clear that, they would need to take either a four- or eight-hour training course, depending on whether they’ve passed a hunter safety class.
Polis said Thursday that he wanted to keep the cost of background checks and training to below $200 per person and that he wanted additional carveouts for people who’d previously been trained with the weapons.
The law does not prohibit the possession of the weapons. It does not apply to most common handguns or shotguns, and lawmakers included a list of other firearms that are exempt from the limitations. The law also would not require anyone to turn in their firearms.
Gun shops can also continue selling firearms covered under the law, even to people who haven’t passed background checks, so long as the weapons have been altered to have a fixed magazine — meaning that they cannot be reloaded as rapidly.
All of the legislature’s 34 Republican lawmakers — along with several Democrats — voted against the bill. Conservatives labeled it an infringement on the Second Amendment and argued it would do little to stop gun violence.
Opponents delivered thousands of petitions to Democrats and to Polis’ office requesting that the proposal be rejected, and some also left fliers at the homes of Democratic lawmakers.
A skeptic of previous proposals to ban firearms at the state level, Sullivan embraced SB-3 as a means to enforce the 2013 magazine ban passed after the 2012 Aurora movie theater shooting, in which Sullivan’s son, Alex, was killed. Other advocates and supporters said the bill seeks to prevent the mass shootings that have become a common feature of American life.
The new law’s limitations would apply to the guns used in the Aurora attack as well as to the weapons used at Columbine High School in 1999, at the Boulder King Soopers in 2021, and in a shooting spree in Lakewood and Denver in late 2021.
As initially drafted, the bill would’ve broadly banned the sale or purchase of any gas-operated gun that accepted detachable magazines — which simultaneously would’ve escalated the magazine ban and enacted a de facto ban on most existing assault weapons.
But Polis balked, and his staff sought to insert a loophole into the measure allowing for sales to continue under certain circumstances.
In a late-night deal, Sullivan and Gonzales eventually acquiesced to the governor’s request. They added in the training and background check requirements after a needed supporter — beleaguered then-Sen. Sonya Jaquez Lewis — was absent ahead of a key vote.
With SB-3, Colorado joins a growing list of states that have either instituted a permitting scheme — meaning requirements that people receive some sort of approval before they can purchase certain weapons — or an outright ban on semiautomatic rifles.
The law will almost certainly be challenged in court, though legal scholars and supporters have argued it stands on solid constitutional footing.
Legislative Democrats have enacted a growing list of firearms regulations, largely in the past few years as the party’s legislative majorities have grown. Sullivan said 40 gun-violence prevention bills have been introduced in recent years, nearly half of which have passed.
Those new laws include a mandatory waiting period and age limit for purchasing firearms, new gun-storage rules and additional gun shop licensing requirements. Lawmakers have also further limited where firearms can be carried and have expanded the legal avenues for a court to temporarily confiscate a person’s weapons.
After signing SB-3 on Thursday, Polis then signed another Sullivan-backed bill intended to help bring federal funding to the state to respond to mass shootings.
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