For a long time, the Supreme Court did its best to avoid the implications of the Second Amendment’s reference to “the right of the people to keep and bear arms.” Its decision today is a constitutional landmark, a triumph for individual freedom and a tribute to the power of ideas.

The decision is the long-awaited result of an intellectual revolution in the legal academy. A generation ago, law professors generally regarded the idea of an individual right to own guns as a dangerous anachonrism.