These four words close the Second Amendment: 'the right of the people to keep and bear Arms, shall not be infringed.' The phrase has sparked decades of legal battles over what restrictions government can impose. The Supreme Court largely ignored the amendment until 2008, when District of Columbia v. Heller struck down DC's handgun ban, ruling the Second Amendment protects an individual right to own guns for self-defense, not just militia service. Two years later, McDonald v. Chicago applied that right against state and local governments. But the Court said 'shall not be infringed' doesn't mean zero regulations—governments can still ban felons from owning guns, prohibit weapons in schools, and require background checks. The debate centers on where the line falls. Gun rights advocates cite the text as an absolute bar, while courts have consistently rejected that reading by pointing to the amendment's opening militia clause and the historical tradition of firearms regulation that the 2022 Bruen decision made the standard test. Courts now scrutinize gun laws using that historical analogue framework, making many modern restrictions harder to defend without clear 18th- or 19th-century precedents.