Background checks in July surged to record-breaking levels before a new law came into effect to increase regulations to buy certain semiautomatic guns.

In the lead-up to the law’s implementation, the month of July saw nearly 60,000 background checks performed, almost triple the figure from the year prior according to the Colorado Bureau of Investigations. Colorado does not track firearms sales, but background checks are required for firearm sales.

Opponents of the state law called it unconstitutional, while supporters argued it would keep some of the most dangerous weapons out of the wrong hands. In the lead-up to its implementation over the weekend, gun owners rushed to purchase firearms before the new restrictions went into place.

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The law, SB25-003, was passed back in 2025 but did not go into effect until August 1. The law concerns semiautomatic firearms, specifically those that use detachable magazines. It requires people who purchase them to complete a safety course and test, and gives sheriffs the ability to block peoples’ access to the firearms.

Proponents for the state measure said it was an important step toward keeping firearms away from people who would use them for mass shootings.

“If you're going to purchase one, you need to be highly trained and particularly concerned about safety and knowing state laws,” Eileen McCarron, co-founder of the gun safety advocacy group Colorado Ceasefire, told The Center Square on the law’s implementation.

The new law does not impact semiautomatic firearms already owned in Colorado.

“This is the worst piece of anti-second amendment legislation that has ever been passed in Colorado,” Huey Laugesen, executive director of the Colorado State Shooting Association, told The Center Square.

The firearms rights group filed a lawsuit, Del Toro V. Polis, in response to SB25-003’s passage into law. The action was launched ahead of the law’s implementation as part of an ongoing effort to overturn the law.

“It's unconstitutional and that's why we are suing to overturn it,” Laugesen said.

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Supporters and opponents alike expressed some confusion around exactly what firearms would be subject to the new restrictions before the law went into effect. One of the most popular firearms, the Glock pistol, is not subject to the new law, despite some speculation otherwise.

McCarron argued that while semiautomatic weapons are not the most common cause of gun violence, they are the most frequently used in mass shootings.

"We, unfortunately, in Colorado are too familiar with massacres," she said.

But to gun rights activists, the law’s confusion spelled proof of a lack of firearm knowledge among the law’s supporters.

“It shows you that the people who wrote this bill don't understand what they're trying to regulate, which is all so often the case with these gun control measures,” Laugesen said.

McCarron said that while Colorado Ceasefire and other proponents for the law were happy at its implementation, they would like to see a full assault weapons ban. She emphasized that the law did not impact firearms already in circulation.

“There's nothing stopping these things from crossing state lines,” McCarron said.