Montana is leading a coalition of 27 states in urging the U.S. Supreme Court to hear and overturn a Washington state law that bans the sale and possession of firearm magazines that hold more than 10 rounds.

The 27 state attorneys general, led by Montana AG Austin Knudsen, filed an amicus brief in Gator’s Custom Guns, Inc. v. State of Washington stating the Washington Supreme Court was wrong to uphold a ban on the magazines in violation of the Second Amendment.

"This case should not have been hard," the brief began.

The AGs argue that "plus-ten magazines are in common use today," with 48% of gun owners possessing the mags and as many as 542 million of them in circulation. The Second Amendment protects the right of citizens to bear arms "that are unquestionably in common use today."

The Washington Supreme Court, however, disagreed.

Yet the Washington Supreme Court joined several other courts in rewriting the Second Amendment and this Court’s precedents to allow hostile jurisdictions to continue infringing on their citizens’ core constitutional right to keep and bear arms," read the amicus brief.

Knudsen said in a statement, "Washington’s failure to properly interpret the Second Amendment and ban plus-ten magazines ignores both history and constitutional precedent. Law-abiding citizens should not be treated like criminals for exercising their right to keep and bear arms for self-defense." 

Louisiana also joined the effort against the 2022 law, which was struck down by a Cowlitz County judge, who ruled it violated the Second Amendment.  

"Shall not be infringed," Louisiana AG Liz Murrill told The Center Square. 

The other states to join the brief: Idaho, Alabama, Alaska, Arkansas, Florida, Georgia, Iowa, Indiana, Kansas, Kentucky, Mississippi, Missouri, Nebraska, New Hampshire, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, West Virginia, Wyoming, and the Arizona Legislature.