That brings us to the license-plate case. A license plate is not an occasional ad for beef and it’s certainly not a monument. It’s a sign, property of the state, that every motorist is required to display visibly at all times on his or her property. A lot of states, like Texas, have decided to cash in on this requirement by letting private groups pay to display messages on “specialized plates.” Is the license plate a First Amendment-free zone where the state can decide what to require each person to “say”—and what to forbid?

In 1977 the Court held that the state of New Hampshire couldn’t arrest a religious objector who covered over the state motto (“Live Free or Die”) on his plate; in the Texas case, the state wants the same “right”—it objects to the Battle Flag, and wants to cover it up. Because the plates are government speech, Scott Keller, the Solicitor General of Texas, told the justices, the state could use them to encourage some messages and groups, and to silence others, for any reason it chose, aesthetic or political—or indeed, for no reason except whim.

The justices didn’t like that answer; they also didn’t like the idea, proposed by the lawyer for the Sons of Confederate Veterans, that a state that sells “specialized” plates must provide one containing any word or symbol, no matter how foul.