Why did the Supreme Court describe self-defense in the home as central to the Second Amendment in District of Columbia v. Heller?

In the 2008 case District of Columbia v. Heller, the U.S. Supreme Court identified self-defense as the "central component" of the Second Amendment because it concluded that the framers of the Constitution understood the right to keep and bear arms to be derived from English common law.1

Writing for the majority, Justice Antonin Scalia argued that this individual right was historically codified in the English Bill of Rights (1689). By interpreting the amendment through this lens, the Court held that the right to possess firearms is not limited to service in a militia but implicitly protects the right of individuals to use arms for the purpose of self-defense within the "hearth and home." Consequently, the Court ruled that the District of Columbia’s prohibition against keeping handguns operable for immediate self-defense in the home was unconstitutional.12