District of Columbia v. Heller (2008)
The U.S. Supreme Court ruled the Second Amendment protects an individual right to keep a firearm for self-defense, and listed felons and the mentally ill as groups whose gun rights can be restricted.
The ruling struck down Washington, D.C.'s handgun ban and opened the door to decades of Second Amendment challenges.
Courts have since debated who counts as “the people” with Second Amendment rights, including adults under 21.
Thomson's case asks whether a 20-year-old counts among “the people” Heller protected.
