Activists on both the left and right have focused intently on every shred of possible evidence that Supreme Court nominee John G. Roberts Jr. would vote to overrule the court's 1973 Roe v. Wade decision that recognized a constitutional right to abortion.

But there has been far less attention to an equally contentious issue that takes up far more of the justices' time each term than abortion: capital punishment. Every death sentence in the country comes before the court not once but twice or more: first on direct appeals, the vast majority of which are brushed aside, and then on habeas corpus challenges claiming constitutional violations at trial or sentencing.

And the substitution of Roberts for Justice Sandra Day O'Connor could make a difference on the death penalty.

O'Connor, who helped draft Arizona's death penalty law as a state senator, was no death penalty abolitionist. In her early years on the Supreme Court, she played a key role in curtailing constitutional appeals by death row inmates.

Recently, however, O'Connor seemed to grow more skeptical of the states' administration of capital punishment. In speeches, she expressed concern that innocent defendants may have been sentenced to death, and she questioned the quality of defense counsel available to those facing capital charges.

These views were reflected in her votes on the court. Though O'Connor had refused to declare capital punishment for the moderately mentally retarded unconstitutional in 1989, she joined a six-justice majority of the court in reaching that result in 2002. In the court's last term, she joined the four most liberal justices in a 5 to 4 ruling that required defense lawyers to dig more aggressively for information that might persuade a jury to choose life imprisonment instead of the death penalty at the sentencing phase of a capital case.

But the available information on Roberts's views about capital punishment is sketchy at best.

In 1980-1981, he served as a law clerk for then-Justice William H. Rehnquist, who strongly advocates removing barriers to rapid capital sentencing -- but in that role Roberts was an aide, not a decision-maker.

During his career in the administrations of Ronald Reagan and George H.W. Bush, he had little to do with criminal justice issues.

As a lawyer in Washington, Roberts played a brief supporting role in one case his law firm handled for free on behalf of a death row inmate in Florida.

He has faced no capital punishment-related cases in his two years as a judge on the U.S. Court of Appeals for the D.C. Circuit.

Perhaps Roberts's most comprehensive statement on the death penalty came in response to questions from Sen. Russell Feingold (D-Wis.) at his 2003 confirmation hearing for the seat he now holds on the D.C. Circuit.

Feingold asked Roberts whether he was "concerned that poor defendants may not receive adequate legal representation, especially at the trial level of a capital case."

Roberts said he did not know much about the situation, but that "it certainly can't be the case that in all cases they receive adequate representation."

He added: "I have long been of the view that whether you're in favor of the death penalty or opposed to it the system would work a lot better to the extent that defendants have adequate representation from the beginning." Roberts said prolonged appeals based on claims of inadequate representation were a major reason "these cases drag out so long."

Then Feingold asked: "Do you think that the current system is fair or do you agree with an ever-increasing number of Americans that it risks executing the innocent?"

Roberts did not answer directly at first, noting that "one thing that is unfair" is that "it's not certain, it's not definite, and there doesn't seem to be any reasonable time limitation." The long delays undermine any deterrent effect the death penalty might have, he said.

Feingold pressed Roberts about "the fact that 100 people have been exonerated, who were already sentenced to death."

Roberts replied that "obviously the first reaction is that the system worked in exonerating them."

Then Feingold asked whether Roberts thought "we've gotten all the ones that are innocent on death row."

When "you're talking about capital punishment, it is the ultimate sanction, and sort of getting it right in most cases isn't good enough. I agree with that," Roberts said.

If he is confirmed, Roberts may get a chance to wrestle with these issues in his first term. The issue of innocence will be before the court this fall in House v. Bell, No. 04-8990. The case involves a death row inmate in Tennessee who has DNA evidence showing that semen found on a woman whom he was convicted of raping and murdering did not come from him.

By a vote of 8 to 7, the Cincinnati-based U.S. Court of Appeals for the 6th Circuit ruled that, under the standards set in a 1995 Supreme Court ruling, this evidence was not sufficient to overturn state court rulings upholding the conviction and sentence.

Thus, the case calls on the court to revisit the 1995 ruling in light of new and better DNA science -- and recent history with DNA-based exonerations of inmates on death row in Illinois.

"Whether a prospective justice believes the states can be trusted with all of this or whether he thinks we need another layer of federal review is going to be an important aspect," said Richard C. Dieter, executive director of the Death Penalty Information Center, which opposes capital punishment.

Supreme Court nominee John G. Roberts Jr., left, fielded questions by Sen. Russell Feingold (D-Wis.) about capital cases during Roberts's 2003 confirmation hearing for the U.S. Court of Appeals for the D.C. Circuit.