# US firearm regulation legal challenges > Live situation record from CLSTR: https://clstr.news/situations/us-firearm-regulation-legal-challenges > Updated: 2026-09-21T15:03:12.000Z. Sources: 7. Developments: 2. Legal challenges regarding firearm regulations are moving through the U.S. court system. The Second Amendment Foundation filed briefs with the Supreme Court to challenge assault weapons bans in Cook County, Illinois, and Connecticut, specifically questioning the legality of banning semiautomatic rifles like the AR-15. Subsequently, the National Rifle Association and the Second Amendment Foundation petitioned the Supreme Court to review Beckwith v. Frey, a case contesting Maine’s three-day waiting period for firearm purchases. This follows a First Circuit Court of Appeals ruling that overturned a previous decision favoring the plaintiffs. In a separate legal development, the Department of Justice’s Office of Legal Counsel issued a memorandum declaring that federal laws prohibiting handgun sales to adults aged 18 to 20 are unconstitutional. While this marks a shift in federal policy, some state officials, such as New York Governor Kathy Hochul, have indicated that state-level prohibitions on handgun sales to teenagers will remain in effect. ## Timeline ### 2026-09-21: Second Amendment groups petition Supreme Court over firearm laws Pro-Second Amendment groups are petitioning the Supreme Court over Maine's firearm waiting periods, while a DOJ memo declares federal bans on handgun sales to 18-20-year-olds unconstitutional. 5 sources. https://clstr.news/cluster/second-amendment-groups-petition-supreme-court-over-firearm-laws ### 2026-09-02: Second Amendment Foundation challenges assault weapons bans in Supreme Court The Second Amendment Foundation has filed Supreme Court briefs challenging assault weapons bans, while new survey data estimates 2.2 million annual defensive gun uses by American civilians. 2 sources. https://clstr.news/cluster/second-amendment-foundation-challenges-assault-weapons-bans-in-supreme-court --- Cite as: US firearm regulation legal challenges. CLSTR, https://clstr.news/situations/us-firearm-regulation-legal-challenges