This column is not — repeat, not — going to argue that our conservative chief justice, John G. Roberts Jr., has morphed into a moderate. With important decisions looming in the remainder of a Supreme Court term that has been unusually quiet so far, there’s little reason to expect surprises from the chief justice’s votes on the constitutionality of partisan gerrymanders or conscience-based opt-outs from anti-discrimination laws. I’m confident that he remains staunchly opposed to affirmative action and equally committed to elevating the place of religion in the public square. And I haven’t forgotten his perfervid opinion dissenting from the court’s 2015 decision declaring a constitutional right to same-sex marriage.

Nonetheless, there’s something going on at the court that bears closer watching than it has generally received. Three times in recent weeks, we have seen Chief Justice Roberts on one side and the reliably right-wing triumvirate of Justices Clarence Thomas, Samuel A. Alito Jr. and Neil M. Gorsuch on the other. That’s not three times out of dozens: The court has issued only eight opinions so far this year, four of them unsigned, along with a handful of what the court calls “miscellaneous orders.” These can be as routine as setting a briefing schedule or as momentous as granting a stay of execution to a death-row inmate.

It was the latter such action last week that calls for taking stock. The court granted a last-minute stay of execution to Vernon Madison, a 67-year-old who has spent the last 32 years on Alabama’s death row for murdering a police officer. He is now disabled by strokes and suffers from vascular dementia that has erased the memory of his crime, although he is evidently still able to understand that the state plans to put him to death for something he did. Supreme Court precedents dating to the 1980s make it unconstitutional to execute someone who lacks the mental capacity to understand the relationship between his crime and his death sentence.

Mr. Madison would seem to fall within that zone, even if not squarely in its center. His case has made numerous trips to the Supreme Court. He came close to execution in May 2016, after the United States Court of Appeals for the 11th Circuit had granted a stay of execution that Alabama then asked the justices to vacate. Four justices — Chief Justice Roberts and Justices Thomas, Alito, and Anthony M. Kennedy — voted to grant the state’s request. But five votes are required to grant or vacate a stay, and three months after the death of Justice Antonin Scalia, the court was tied at 4 to 4, and the stay remained in place, with the case returned to the lower courts for more proceedings. Eventually, Mr. Madison ran out of appeals, and Alabama set Jan. 25 as a new execution date.