An appeals court Friday upheld a decision to throw out a legal challenge to Massachusetts's assault weapons ban.

"This case concerns an issue of paramount importance," the 1st Circuit Court of Appeals ruling said, according to The Boston Globe. "In the wake of increasingly frequent acts of mass violence committed with semiautomatic assault weapons and [large-capacity magazines], the interests of state and local governments in regulating the possession and use of such weapons are entitled to great weight."

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Gun rights proponents and weapons retailers contended in the lawsuit that the AR-15 rifle is not fully automatic, so it should not be classified as a military-style assault weapon, according to the Globe. It also argued that the government's enforcement notice could penalize people who purchased duplicate guns before 2016.

Last year, a federal judge threw out the lawsuit, rejecting claims that it violated Second Amendment rights.

Massachusetts Attorney General Maura Healey (D) praised the ruling on Twitter, calling it "a victory for families" and "a defeat for the gun lobby."

#BREAKING In a defeat for the gun lobby and a victory for families everywhere, the First Circuit has upheld the Massachusetts assault weapons ban. Once again, the courts have agreed that the people of our state have the right to protect themselves by banning these deadly weapons. pic.twitter.com/UiZo8VPGc7 — Maura Healey (@MassAGO) April 26, 2019

Sen. Elizabeth Warren Elizabeth WarrenDimon: Wealth tax 'almost impossible to do' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context Democrats shoot down talk of expanding Supreme Court MORE (D-Mass.), who is running for president, also celebrated the ruling and Healey's "courageous work to stand up to the gun lobby & keep weapons of war off our streets."

Great news for Massachusetts families & terrible news for the @NRA! I’m deeply grateful for @MassAGO Maura Healey’s courageous work to stand up to the gun lobby & keep weapons of war off our streets. MA is a leader in gun safety & the federal govt should follow its example. https://t.co/q52MfX8jZi — Elizabeth Warren (@SenWarren) April 27, 2019

Healey in 2016 widened the definition of "copies or duplicates" of AR-15s and other semi-automatic weapons that are banned by a 1998 state law, according to USA Today.