Denver, CO — Gun rights organizations have filed a lawsuit challenging Colorado’s newly implemented tax on firearms and ammunition, arguing that it violates the Second Amendment.

The 6.5% excise tax, which took effect Tuesday, was approved by 54% of voters in November under Proposition KK. The tax applies to firearm vendors on the sale of guns, ammunition, and firearm parts.

The lawsuit, filed Monday in Denver County District Court, describes the tax as an unconstitutional “infringement-by-taxation scheme,” asserting that the financial burden will ultimately fall on Colorado residents purchasing firearms and ammunition.

“The tax on the exercise of Second Amendment rights implicates conduct protected by the Second Amendment’s plain text by adding to the cost of acquiring a firearm,” the complaint states. The legal challenge is backed by the Colorado State Shooting Association, the Firearms Policy Coalition, the Second Amendment Foundation, Magnum Shooting Center in Colorado Springs, and Zachary Langston, an El Paso County resident and NRA member.

Opponents argue that Coloradans already pay state and local sales taxes on firearms, and the new excise tax unfairly targets law-abiding gun owners.

“This tax is a direct attack on our Second Amendment rights,” the Colorado State Shooting Association said in a statement. “Now the state is piling on a punitive gun tax that exclusively targets responsible gun owners.”

The new tax is in addition to a federal excise tax on firearms and ammunition, which ranges from 10% to 11%. Colorado officials estimate the measure will generate $39 million in revenue annually.

The lawsuit names Colorado Department of Revenue Executive Director Heidi Humphreys and El Paso County District Attorney Michael J. Allen as defendants.

John Commerford, executive director of the NRA’s Institute for Legislative Action, condemned the tax, calling it “an overt assault on the Second Amendment rights of law-abiding Coloradans and a deliberate attempt to discourage the exercise of constitutionally protected freedoms.”

The lawsuit comes amid broader gun control efforts in the state. Recently, the Colorado General Assembly passed a series of gun-related measures, including restrictions on semiautomatic rifle purchases without a firearm education course, raising the minimum age to purchase ammunition from 18 to 21, and requiring liability insurance for gun shows.

It remains to be seen how the courts will rule on the lawsuit, but the case is expected to be a significant legal battle over firearm taxation and Second Amendment rights in Colorado.