Chief Justice Roberts writes the opinion, with only Justice Alito dissenting. Justice Breyer has a concurring opinion. From the Roberts opinion:
The picketing was conducted under police supervision some 1,000 feet from the church, out of the sight of those at the church. The protest was not unruly; there was no shouting, profanity, or violence....Clearly, this is the right outcome.
Given that Westboro’s speech was at a public place on a matter of public concern, that speech is entitled to “special protection” under the First Amendment. Such speech cannot be restricted simply because it is upsetting or arouses contempt. “If there is a bedrock principle underly- ing the First Amendment, it is that the government may not prohibit the expression of an idea simply because society finds the idea itself offensive or disagreeable.” Texas v. Johnson, 491 U. S. 397, 414 (1989). Indeed, “the point of all speech protection . . . is to shield just those choices of content that in someone’s eyes are misguided, or even hurtful.” Hurley v. Irish-American Gay, Lesbian and Bisexual Group of Boston, Inc., 515 U. S. 557, 574 (1995)....
Speech is powerful. It can stir people to action, move them to tears of both joy and sorrow, and—as it did here— inflict great pain. On the facts before us, we cannot react to that pain by punishing the speaker. As a Nation we have chosen a different course—to protect even hurtful speech on public issues to ensure that we do not stifle public debate. That choice requires that we shield West- boro from tort liability for its picketing in this case.
AND: Alito, the lone dissenter, stresses the value of the tort called "intentional infliction of emotional distress":
Respondents’ outrageous conduct caused petitioner great injury, and the Court now compounds that injury by depriving petitioner of a judgment that acknowledges the wrong he suffered.Breyer's short concurrence makes the point that the decision is limited to in-person picketing about matters of "public concern." In adding that the Court "does not examine in depth the effect of television broadcasting" and "internet postings," I get the sense that he's looking ahead to cases about bullying.
In order to have a society in which public issues can be openly and vigorously debated, it is not necessary to allow the brutalization of innocent victims like petitioner.