A Tennessee death-row inmate can use DNA evidence to attempt to show his innocence 20 years after he was convicted of murdering a neighbor, the Supreme Court ruled Monday.

The high court's decision is significant because numerous exonerations in recent years of death-row and other criminal defendants through DNA testing have raised concerns among civil libertarians, prosecutors and Supreme Court Justice John Paul Stevens that an innocent person may be executed, or already has been.

Justice Anthony M. Kennedy, writing for the court, said the evidence in the case was a "close" call for a jury. But he said that inmate Paul Gregory House could proceed with a lawsuit in federal court claiming innocence for the murder of Carolyn Muncey, a young mother of two, in Union County, Tenn., in July 1985.

Click here to read the opinion (pdf).

Twenty years after his conviction, DNA testing revealed that semen found on the murder victim's nightgown and underwear belonged to her husband, not House.

"This is not a case of conclusive exoneration," Kennedy wrote on behalf of himself and four other justices.

Chief Justice John Roberts and Justices Antonin Scalia and Clarence Thomas dissented. Justice Samuel Alito did not participate in the case because it was argued before he joined the high court.

Kennedy said jurors could find reasonable doubt because DNA evidence points to Muncey's husband as a suspect and because small blood stains found on House's jeans may have spilled on the pants from vials of blood taken from Muncey during an autopsy.

House, who was on parole for a sex offense in Utah, was convicted of luring Muncey from her home by telling her that her husband, Hubert, had been hurt in a car accident. Her body was found the next afternoon in an area where witnesses had seen House.

His original lawyer failed to locate several witnesses who said years later that Hubert Muncey had abused his wife, had fought with her the night of her murder and had confessed later to killing her.

House's case had generated excitement in legal circles because it gave the high court a chance to jump into the national debate over DNA testing and how courts should deal with advances in evaluations of biological evidence left at crimes scenes long ago.

"Although the issue is close, we conclude that this is the rare case where — had the jury heard all the conflicting testimony — it is more likely than not that no reasonable juror viewing the record as a whole would lack reasonable doubt," Kennedy wrote.

Kennedy said that House's revelations about DNA and the blood stains are enough to overcome strict standards that must be met before prisoners are allowed to re-argue issues of innocence long after their convictions.

But Roberts, in the dissent, disagreed. He said the majority had ignored a trial judge's determination that House and several of his witnesses were unreliable. Roberts also noted that the trial judge had found that Muncey's autopsy blood was spilled on House's jeans after the FBI already had determined that the blood on his pants belonged to the victim.

"Witnesses do not testify in our courtroom, and it is not our role to make credibility findings and construct theories of the possible ways in which Mrs. Muncey's blood could have been spattered and wiped on House's jeans," Roberts wrote.

The chief justice took a different approach than the majority, which based its decision on its belief that at least one juror would have reasonable doubt about the evidence. Roberts said he believed that at least one juror would have voted to convict House.

The case is House v. Bell, 04-8990.