Whatever side of the Second Amendment controversy you may be on, the clear winner in District of Columbia v. Heller (striking down a Washington, D.C., ban on hand guns) was intentionalism, the thesis that a text means what its author or authors intend. The text in dispute is 27 words long, and it is cited in the opening pages of each of the three opinions: “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear arms, shall not be infringed.” None of the words in this sentence is...