It’s not easy to get to the right of Justice Samuel A. Alito Jr. when it comes to the rights of criminal defendants. In fact, for a long time I thought it was impossible. The late Justice Antonin Scalia’s robust view of aspects of the Fifth and Sixth Amendments led him to vote to overturn criminal sentences with some regularity. Justice Clarence Thomas, who views civil forfeiture as imposing an “excessive fine” in violation of the Eighth Amendment, has occasionally done so as well. Justice Alito: a millimeter this side of never.

And then, two weeks ago, came the court’s long-anticipated ruling in Foster v. Chatman. In an opinion by Chief Justice John G. Roberts Jr., the Supreme Court overturned a 30-year-old murder conviction, ruling that racial discrimination infected the selection of the all-white Georgia jury that found a black man guilty of a white woman’s murder. The vote was 7 to 1. The dissenter was Justice Thomas. His vote, along with the contorted 15-page opinion that explained it, was one of the most bizarre performances I have witnessed in decades spent observing the Supreme Court. As the post-Scalia Roberts court continues to take shape — and in advance of the final onslaught of decisions to come in the next few weeks — it’s worth pausing to consider this vote and the role of the justice who cast it.

I should make clear what I’m not saying. I’m not suggesting that because Justice Thomas is the court’s only black member, he has some kind of heightened obligation to take up the cause of black defendants, or black anyone else. Approaching his 25th anniversary on the court, he has made his rejection of such a role corrosively clear. After all, this is a man who, speaking from deeply felt personal experience, has called affirmative action a “cruel farce.” And three years ago, in Shelby County v. Holder, he not only joined the 5-to-4 majority in eviscerating the Voting Rights Act, but wrote in a separate opinion that he thought the court should have sliced even deeper into the statute. I almost think Justice Thomas revels in his chosen role as the anti-Thurgood Marshall, the civil rights hero whose seat he took on Oct. 23, 1991.

Granting all that, Foster v. Chatman was not just any criminal case. Yes, of course it was importantly about race. But it was also about something just as deep, or even deeper: the Supreme Court’s commitment to its own principles. This case posed the question: does the court mean what it says?