Is there a constitutional right not to be executed for a crime of which you’ve been convicted but can now prove your innocence?

The question answers itself: Of course there is. But Assistant Attorney General Margaret Griffey of Texas gamely maintained the contrary in an Oct. 7 argument before the Supreme Court in Herrera v. Collins.

"Suppose you have a videotape which conclusively shows the person is innocent, and you have a state which, as a matter of policy or law or both, simply does not hear new evidence claims," Justice Anthony Kennedy asked. "Is there a federal constitutional violation?"

"No, Your Honor, there is not," Griffey responded, asserting that such an execution "would not be violative of the Constitution."

Wow. It is a measure of the death penalty’s current vogue that such a position could be maintained before the nation’s most august tribunal without provoking gasps of disbelief.

But the issue in Herrera is not quite as simple, and the state’s position not quite as absurd, as this exchange might make it seem. Rather, as Solicitor General Kenneth Starr contends in the Bush administration’s amicus brief, the central question is whether the settled constitutional rule against executing an innocent defendant "requires a state to establish a judicial, post-conviction mechanism for entertaining a prisoner’s challenge to his conviction on the basis of newly discovered evidence."

Starr’s answer is no: The states are not required by the Constitution-and federal judges are not permitted by the habeas corpus statute-to afford any prisoner even the most cursory hearing into newly discovered evidence, no matter how much doubt it may cast on his guilt.

If this view prevails, it will help clear the way for the executions of maybe five, maybe 10, maybe 20 innocent, erroneously convicted defendants over the next decade or two. Do I exaggerate? It’s impossible to say with precision how many innocent defendants have been or will be executed. But it’s clear that some have been, according to Hugo Adam Bedau, a Tufts University philosophy professor who has long been the leading researcher into wrongful convictions of innocent capital defendants.

In a new book, In Spite of Innocence, Bedau and two co-authors collect 416 cases between 1900 and 1991 in which defendants convicted of capital crimes-including 23 who were executed"–have later been proven innocent, or at least shown to have strong claims of innocence.

Bedau estimates, in an interview, that perhaps one percent of the 2,600 people now on death row are, in fact, innocent of the murders of which they stand convicted. That would come to 25 or so innocent individuals. They would probably all be dead already if Chief Justice William Rehnquist had controlled the Court over the past two decades.

Now Rehnquist and his allies are doing everything they can to depopulate death row by accelerating the pace of executions. But so far the Court has qualified its decisions cutting back federal habeas review by stressing that any evidence suggesting actual innocence should receive the most careful scrutiny.

Leonel Herrera’s case will show whether the Court really means that, or whether it is so eager to facilitate the forced march into the death chambers that it will allow an execution to proceed with no judicial hearing of any kind into new evidence that, at first blush, seems strikingly significant. In affidavits, four witnesses have sworn that the two Texas police officers whom Leonel Herrera was convicted of murdering 11 years ago were, in fact, killed by Leonel’s now-dead brother, Raul Herrera Sr.; that Raul was using Leonel’s car that night; and that Leonel was neither present nor involved.

Raul Herrera Jr., son of Raul Sr. and nephew of Leonel, claims in an affidavit signed early this year that (at the age of nine) he saw his father shoot the two police officers. Raul Sr.’s former attorney (who is also a former Texas state judge) and two other men have sworn that Raul Sr. told them that he, not Leonel, had killed the two officers. Leonel’s theory is that the murders grew out of a dispute between Raul Sr. and David Rucker, one of the murdered officers, who (Leonel says) was part of a drug ring with the Herrera family.

The new witnesses’ stories are, of course, more than a little bit suspect, because they came forward after so many years, because they conveniently finger a dead man, and because their accounts are somewhat inconsistent with each other and with Leonel Herrera’s original trial strategy. Moreover, the convictions are supported not only by two (albeit shaky) eyewitness identifications of Leonel as the killer, but also by his guilty plea to one of the murders (which he claims was extorted by beatings) and by a highly incriminating letter found in his pocket when he was arrested. "I am terribly sorry for those I have brought grief to their lives," Leonel Herrera wrote. "What happened to Rucker was for a certain reason…. He was in my business, and he violated some of its laws and suffered the penalty, like the one you have for me when the time comes."

On balance, it seems unlikely that Leonel Herrera ultimately will be able to overcome the presumption that his convictions are valid. But don’t we as a society owe him and his new witnesses some kind of hearing before sending him to his death? Shouldn’t a judge at least listen to what Raul Herrera Jr. and the others have to say and see how they bear up under cross-examination? That would take a few hours of court time. Should not a condemned man be given those few hours to try to show his innocence?

On this point, the laws of Texas and many other states have not caught up with the death-penalty jurisprudence beginning with Gregg v. Georgia in 1976, which requires great precautions to prevent wrongful executions. Texas law bars courts from hearing claims of innocence based on newly discovered evidence more than 30 days after sentencing. The only recourse for a prisoner like Herrera is a petition for executive clemency.

But the clemency process is no substitute for a judicial hearing. Once a defendant has been condemned, a fearsome momentum develops inside the executive bureaucracy to get on with the execution, no matter what new evidence may be brought forth. No death-row prisoner has won executive clemency in more, than 20 years in Texas:

The Supreme Court should hold that it violates due process to execute a person without a judicial hearing on any newly discovered evidence that, if believed, would cast substantial doubt on his guilt; if the state will not provide such a hearing, federal habeas relief should be available.

Providing such a modest safeguard against the risk of executing (or continuing to imprison) innocent people would not burden courts with cumbersome new proceedings every time a prisoner came up with a far-fetched claim. While there might (as the state warns) be many such claims, the frivolous ones could be easily spotted and quickly disposed of. And no new federal habeas proceedings would be required in those states that already provide adequate post-conviction hearings to weigh newly discovered evidence.

Herrera’s claim seems substantial enough to require at least a hearing of the four new witnesses. If the judge found them to be incredible, Herrera’s petition (and any appeals) could then be dismissed without further ado. If, on the other hand, the judge found the witnesses credible and their evidence substantial, that would call for a more detailed hearing to determine whether the new evidence is strong enough to overcome the original convictions’ presumption of validity. If so, Herrera would be entitled to a new trial.

Herrera appears to be facing something of a stacked deck, however: The justices have already voted, 5-4, to let him die. The four who voted in February to take up the case could not get a fifth vote to stay Herrera’s execution. (He then got a stay from a Texas court.) So Herrera may be doomed unless one of the other five is willing, in effect, to admit having voted initially to allow the execution of a man who just might be innocent.

But even those justices who think Herrera has a weak case should not use it to make bad law. The ultimate question is not the guilt or innocence of this particular death-row prisoner. It is whether, as a general proposition, a proffer that on its face raises a nagging doubt as to a prisoner’s guilt requires the judiciary to hear what the new witnesses have to say before allowing the prisoner’s execution to proceed. The question answers itself.