Gun rights groups in Maine have filed a lawsuit challenging the constitutionality of a new law on waiting periods for most gun purchases.

One of the plaintiffs’ attorneys was part of the US Supreme Court’s landmark Bruen decision, which established a new test for evaluating the constitutionality of firearms regulations.

The three-day waiting period law was passed by the Maine Legislature this year in response to the mass shooting in Lewiston in 2023. Supporters argued the law would provide a cooling-off period that would help reduce suicides, which accounts for nearly 90% of gun deaths in Maine.

The lawsuit, filed in U.S. District Court in Bangor, says the law infringes on residents’ exercise of their Second Amendment rights by imposing a restriction unrelated to determining whether individual gun buyers should be denied access to firearms such as background checks.

The plaintiffs include gun dealers and Andrea Beckwith, who runs a self-defense training program that teaches women how to use firearms. The lawsuit says one of the women injured in the Lewiston shooting is one of Beckwith’s clients. It also says the law delays gun sales to those most in need of protection, including victims of domestic violence.

Paul Clement is among the lawyers assisting in the trial. He led the 2022 Bruen v. New York case, which gun rights groups have since used to challenge firearm regulations. In the ruling, the U.S. Supreme Court effectively created a new test for the constitutionality of gun regulations, requiring such laws to demonstrate that they are consistent with the nation’s historic tradition of regulating firearms.

Gun control groups have argued that regulating firearms for public safety is inherent in the nation’s founding principles. That argument was persuasive this summer in Vermont, where a federal judge blocked gun rights groups’ challenges to a pair of gun laws, including a waiting period standard passed last year.

In his ruling, Justice William K. Sessions III wrote that “the plain text of the Second Amendment does not protect the right to immediately purchase a firearm.”

The plaintiffs in the Maine lawsuit argue that the waiting period law “has no historical pedigree” and would have been “unimaginable at its inception.”

The lawsuit has long been promised by the Sportsman’s Alliance of Maine and Gun Owners of Maine, who organized events at gun shows summer to help fund it.

Maine joined 12 other states in passing such a law. Violators face a fine of $500 for a first offense and $1,000 for subsequent violations. The proposal was sponsored by Sen. Peggy Rotundo, D-Lewiston, and Gov. Janet Mills allowed it to become law without her signature.

It was one of two gun regulation proposals that became law in response to the Lewiston mass shooting. The other, backed by Mills, extended background checks to private gun sales.