The right to keep arms refers to the Second Amendment's protection of firearm ownership, distinct from the right to 'bear' (carry) them in public. In District of Columbia v. Heller (2008), the Supreme Court ruled 5-4 that the Second Amendment protects an individual right to keep handguns in the home for self-defense, striking down Washington D.C.'s total handgun ban and requirement that rifles be kept unloaded or disassembled. Justice Antonin Scalia wrote that 'keep arms' meant possessing functional weapons ready for use, not locked up or disabled. The decision rejected the century-old view that the Second Amendment only protected state militias. McDonald v. Chicago (2010) applied this right against states through the 14th Amendment. Courts still allow some limits: bans on felons owning guns, background checks, and prohibitions on machine guns or sawed-off shotguns. The 'keep' vs. 'bear' distinction matters in cases about storage requirements, safe-storage laws, and whether assault weapon bans violate the Second Amendment—with courts still working out where those lines fall after Heller and the 2022 Bruen decision.