A coalition of 19 US attorneys general, including California’s Rob Bonta, filed an amicus brief in the US Supreme Court on Wednesday backing assault weapons laws in Connecticut and Cook County, Illinois.
The brief, filed in Viramontes v. County of Cook, urges the Court to uphold appellate rulings that the challenged laws are consistent with the Second Amendment and the nation’s historical tradition of regulating uniquely dangerous weapons, the California Department of Justice said.
The filing is one of a number of amicus briefs submitted on the docket of No. 25-238 on the same day. Others came from the Cook County parties, the Commonwealth of Virginia, the American Academy of Pediatrics and a group of members of Congress.
The states’ brief is styled as that of Massachusetts, New Jersey, 16 other states and the District of Columbia. It says it was filed to explain why the county’s and Connecticut’s regulation of the sale and possession of assault weapons is “wholly consistent with the Second Amendment”.
The coalition argues that the AR-15 platform and similar semiautomatic rifles are uniquely dangerous because their features facilitate assaultive mass killing and are poorly designed for self-defence.
It also asks the Court to reject the petitioners’ argument that the Second Amendment bars laws restricting any weapon, regardless of dangerousness, once it has reached “some arbitrary popularity threshold”.
The brief says that outcome would be dangerous, illogical and ahistorical, and would encourage manufacturers to flood communities with new dangerous weapons before a legislature can act.
Bonta said: “Assault weapon laws restrict a small and uniquely dangerous category of weapons that have proven to be mass shooters’ weapon of choice for a reason.”
The brief argues that the Court’s Second Amendment framework lets states address the “distinctively modern” nature of mass shootings. It says assault weapons like the AR-15 were designed to kill and were used disproportionately in the deadliest mass shootings.
In a sample of mass shootings with at least 20 fatalities from 1991 to 2022, 75% involved assault weapons, the brief says. Bonta separately said three-quarters of mass shootings with 10 or more victims from 2012 to 2022 involved an assault weapon.
On the test of how and why a law addresses misuse, the brief says AR-15s and M-16s firing the same ammunition have the same effective range.
Connecticut enacted its first assault weapons law in 1993 and expanded it in 2013 after the December 2012 shooting at Sandy Hook elementary school, the California Department of Justice said. California signed its first restriction into law in 1989 after the Cleveland Elementary School shooting in Stockton.
The release said 10 other states and several cities now generally restrict the sale, manufacture and possession of assault rifles, including the AK-47 and AR-15.
The Court consolidated the cases for briefing and oral argument on 30 June, the docket shows. On 15 July it extended the deadline for petitioners’ merits brief to 28 August and for respondents’ briefs to 21 October.
Petitioners filed on 28 August. Briefs from Cook County and from Connecticut’s public protection commissioner were not accepted for filing on 21 October, with corrections due on 26 October. Cook County’s brief was submitted on 27 October.
The Solicitor General filed a brief as amicus curiae on 4 September and moved on 9 September for leave to take part in oral argument.
Joining Bonta on the brief are the attorneys general of Arizona, Colorado, Delaware, the District of Columbia, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont and Washington.