Under the Constitution, all criminal suspects are entitled to due process of law. But when a defendant is charged with a capital crime — a crime so severe that it can be punished by death — ordinary due process isn’t enough. The level of required procedural safeguards for the accused rises to one of super due process. Now, in the case of United States v. Dzokhar Tsarnaev, the Supreme Court has agreed to decide whether the most infamous murder defendants must be granted even greater protection.

The death penalty has long been a contentious topic in American life. A majority of the public has consistently expressed support for executing murderers, but that majority has shrunk considerably in recent years, and in many states capital punishment has been abolished.

When Dzhokhar Tsarnaev was indicted for the 2013 Boston Marathon bombings, however, there was little ambivalence about fate he deserved. Fully 70 percent of Americans were in favor of putting Tsarnaev to death if he was found guilty. Support for executing him cut across ideological, racial, and gender lines. That support extended to the Obama-Biden administration, which prosecuted Tsarnaev in federal court and insisted on seeking the death penalty.

In theory, sentences of death are supposed to be reserved for the most monstrous killers — the “worst of the worst.” In real life, it isn’t always clear if a defendant fits that description.

But it certainly fit Tsarnaev. Inflamed by jihadist fanaticism, he and his brother Tamerlan detonated shrapnel bombs at the marathon finish line, causing what the First Circuit US Court of Appeals described as “battlefield-like carnage,” in which “blood and body parts were everywhere.” Three bystanders — graduate student Lingzi Lu, restaurant manager Krystle Campbell, and 8-year-old Martin Richard — were killed. Hundreds of others were maimed. As Copley Square filled with screams of pain and panic, Tsarnaev headed to a grocery store to buy milk. Later, he and Tamerlan gunned down an MIT campus officer at point-blank range.

Tsarnaev’s legal team didn’t dispute that he had committed the horrific crimes with which he was charged: “It was him,” defense attorney Judy Clarke said in her opening statement to the jurors. Tsarnaev himself admitted that he had committed multiple murders and caused “irreparable damage.”

On April 8, 2015, he was found guilty on all 30 charges brought against him. Five weeks later, the jury returned a verdict of death.

Yet last summer, the Court of Appeals threw out Tsarnaev’s death sentence. It ruled that District Judge George O'Toole Jr., who ran the trial, “did not meet the standard” of fairness required in selecting the jury, since he neglected to examine each potential juror’s “kind and degree” of prior exposure to the case. In other words, it held that Tsarnaev was denied due process and an impartial jury.

Was he, though?

In fact, O'Toole went to extraordinary lengths to ensure that Tsarnaev would get a fair trial. He began by summoning 1,373 potential jurors, each of whom was required to answer 100 questions, many of them quite personal, about their lifestyle, background, education, employment, family, and religion. They were asked about their social-media habits, their views of lawyers and police, their political activism, and their opinion of Muslims and immigrants. They had to itemize the newspapers, talk shows, and TV broadcasts they got information from, and were probed about what they may have read, heard, said, or written about the marathon bombing.

Based on their answers, the judge eliminated all but 256 of the prospective jurors, each of whom was individually interviewed over the next month, with considerable input from defense lawyers, before a jury was finally impaneled. When some of O'Toole’s pretrial rulings were appealed, the First Circuit backed him up; his jury-selection process, it said, had been “thorough and appropriately calibrated to expose bias, ignorance, and prevarication.”

Yet that only scratches the surface of the due process protections extended to Tsarnaev.

As with all capital defendants in federal court, he was entitled to two lawyers, one of whom had to be an expert in death-penalty cases. He was given money to pay for experts and jury consultants. His lawyers were granted 20 peremptory challenges (the right to reject a potential juror without giving a reason). He was protected too by the unanimity requirement — Tsarnaev could be found guilty only if all 12 jurors agreed that he committed the crimes and that any mitigating factors in his defense were outweighed by aggravating factors and that the appropriate penalty was not life imprisonment but death. Had a single juror disagreed, Tsarnaev would not have been sentenced to death and prosecutors could not have retried him.

So why did the appeals court overturn the death sentence? Because, it claimed, in such a “high-profile case” the judge should have delved even more deeply into what potential jurors might have gleaned from the media. “Learning that prospective jurors read, say, The Boston Globe daily and have seen a lot of coverage about the case,” said the court in its opinion, “is not the same as learning that they read Globe articles quoting civic leaders saying Dzhokhar should die.”

It’s a bizarre objection. Yes, jurors who followed coverage of the case would likely have seen stories quoting supporters of executing Tsarnaev. They were equally likely to have learned of prominent figures who opposed punishing him with death. Requiring prospective jurors to disclose every opinion expressed in every story they may have read or viewed about an event of such vast public interest is not a formula for making juries more impartial. But it’s an excellent way to make jury selection more intrusive and time-consuming.

However the Supreme Court rules, nothing will change the fact that Tsarnaev is guilty of one of the worst atrocities in Boston’s history. Or the fact that an impartial jury, after weighing all the evidence, unanimously agreed that for the terrible crimes he committed, he deserves the worst penalty our system of justice allows. Tsarnaev was not deprived of due process. He ought to be deprived of his life.

(Jeff Jacoby is a columnist for The Boston Globe).