BOSTON (AP) — No sooner had Massachusetts Gov. Maura Healey signed a sweeping new firearms bill into law last month than gun rights activists filed a lawsuit challenging it, calling the measure an “historic attack on our civil rights.”

Activists are also hoping to place a question on the 2026 ballot to repeal the law, which expands the state’s already tough gun restrictions. It was enacted in part as a response to the Supreme Court’s 2022 Bruen decision declaring citizens have a right to carry firearms in public for self-defense.

The Massachusetts measure cracks down on privately made, unserialized “ghost guns,” criminalizes possessing bump stocks and trigger cranks, requires applicants for a gun license to complete live-fire training, updates the state’s tests for what makes a firearm an assault-style weapon and requires an advisory board to provide a ongoing list of prohibited weapons.

The measure also expands the state’s “red flag” law to let police as well as health care and school officials alert the courts if they believe someone with access to guns is a danger and should have their firearms taken away, at least temporarily.

People looking to suspend the law from taking effect until a potential 2026 referendum on it will need to file at least 49,716 signatures from registered voters, which will also help guarantee the question is placed on the ballot. Healey could block any temporary suspension of the law by pushing for an “emergency preamble” putting it into effect immediately.

The federal lawsuit by gun advocates argues the law is unconstitutional, characterizing it as “onerous firearms legislation that imposes sweeping arms bans, magazine restrictions, registration requirements, and licensing preconditions that are as burdensome as they are ahistorical.”

The suit — which cites the Bruen decision — asks the federal court to issue a temporary restraining order or preliminary injunction barring the state from enforcing the “burdensome licensing regimes on the possession and carry of firearms for self defense.”

Jim Wallace, executive director of the Massachusetts Gun Owners Action League, a local affiliate of the National Rifle Association, said the group sued in federal court because there “is no hope for any help within the Massachusetts court system.”

He suggested the lawsuit is just the start of a wider legal effort to peel back elements of the law piece by piece, saying it’s too expansive for one court to take it on all at once.

“It’s not about crime. It’s not about accidents. It’s not about suicides,” he said. “It’s a bigoted act against 10 percent of the state’s population,” referring to gun owners.

Democratic state Rep. Michael Day, one architect of the legislation, said he’s confident it can withstand the legal challenges. He predicted voters would back the law if the choice is put on the 2026 ballot.

“We’re trying to save lives,” he said. “One of the reasons people live in Massachusetts is that they can walk down the street without someone coming up on their side and menacing them.”

Cody Jacobs, a lecturer at Boston University School of Law, said the measures that deal with increased licensing requirements aren’t excessively burdensome, don’t prevent gun ownership and don’t infringe on Second Amendment rights.

“Other training requirement for gun owners have been upheld by the courts,” he said. “I’d be pretty surprised if this would be overturned.”

The Massachusetts law prohibits people who aren’t part of law enforcement from carrying guns at schools, polling locations and government buildings. It also requires those applying for a license to carry firearms to demonstrate a basic understanding of safety principles and provides local licensing authorities with relevant mental health information.

District attorneys would be able to prosecute people who shoot at or near homes, which also seeks to ensure people subject to restraining orders no longer have access to guns.

The new law also expands the definition of “assault weapons” to include known assault weapons and other weapons that function like them. It bans the possession, transfer or sale of assault-style firearms or large-capacity feeding devices.

The law also bans issuing a license to carry a machine gun except for firearms instructors and bona fide collectors, and criminalizes possessing parts that are intended to make weapons more lethal by adding them to the machine gun statute. Such parts include bump stocks and rapid-fire trigger activators.

The Supreme Court this summer struck down a federal Trump-era ban on bump stocks.