An image of a "stabilizing brace" attached to an AR-type pistol shown in a training presentation from the Bureau of Alcohol, Tobacco, Firearms and Explosives. Republican attorneys general are suing the Biden administration in an effort to block a new rule regulating the braces.
CNN  — 

A coalition of primarily GOP-led led states sued the Biden administration Thursday in an effort to block a new federal rule that subjects pistol-stabilizing braces to additional regulations, including higher taxes, longer waiting periods and registration.

The rule, announced earlier this year by the Bureau of Alcohol, Tobacco, Firearms and Explosives, went into effect on January 31. Gun control proponents have argued that stabilizing braces effectively transform a pistol into a short-barreled rifle, which is heavily regulated under the National Firearms Act.

But in the lawsuit filed by 25 Republican state attorneys general, a Second Amendment advocacy coalition and two of its members, and a disabled gun owner who uses the stabilizing braces, the plaintiffs argue the regulations are “arbitrary and capricious” and are not covered by the 1934 law or the Gun Control Act of 1968.

“The rule regulates pistols and other firearms equipped with stabilizing braces, even though the text, structure, history, and purpose of the NFA and GCA show that the statute does not regulate such weapons,” states the lawsuit, which names US Attorney General Merrick Garland, the ATF and its director as defendants.

ATF declined to comment on the lawsuit. CNN has reached out to the Justice Department for comment on the suit.

The coalition of states challenging the rule is led by West Virginia Attorney General Patrick Morrisey, who said Thursday during a news conference announcing the suit that the ATF’s new rule “is also another case of a federal agency not staying in its lane and doing the job the Constitution clearly delegates to Congress – writing laws.”

“Let’s call this what it is: An effort to undermine Americans’ Second Amendment rights,” he said. “This is an egregious final rule turning millions of common firearms accessories into ‘short-barreled rifles.’ This is a completely nonsensical regulation.”

According to the new rule, manufacturers, dealers and individual gun owners have 120 days to register tax-free any existing short-barreled rifles covered by the rule. They can also remove the stabilizing brace or surrender covered short-barreled rifles to the ATF, the agency said.

Restrictions on stabilizing braces have been hotly debated after they were proposed by the ATF in 2020, when the bureau suggested a new rule that would regulate pistol braces under the NFA. The 2020 proposal sparked a major backlash from groups such as the National Rifle Association.

The regulations challenged on Thursday were given new life in 2021 after pistols with stabilizing braces were used in mass shootings in Boulder, Colorado, and in Dayton, Ohio. At the time, Garland unveiled several proposals aimed at curbing gun violence, including reupping the restriction on pistol braces.