The case before the court involves Paul Gregory House, who was convicted in the July 1985 abduction, attempted rape and murder of Carolyn Muncey, a young mother of two, in Union County, Tenn., north of Knoxville.
House, who was on parole for a sex offense in Utah at the time, was convicted and sentenced to death.
Twenty years later, DNA tests, not available at the time of House's conviction, revealed that semen found on Muncey's nightgown and underwear belonged to her husband.
But the justices didn't focus on the DNA evidence until the end of the hour-long argument. Chief Justice John Roberts, in an exchange with Tennessee's lawyer, stressed that the justices aren't being asked to second-guess the jury that convicted House.
Instead, Roberts said, the justices are looking at "the standard of review question" for lower courts to determine how to weigh new evidence of innocence.
"This is another opportunity for the justices to define and to refine procedural rules in death penalty cases in ways that would directly impact the lives of capital defendants," says CBSNews.com Legal Analyst Andrew Cohen. "The court here has to decide how receptive federal and state lower courts ought to be to the use of DNA evidence after a conviction to try to establish the convict's innocence."
For most of the session, Justice Antonin Scalia, a proponent of curbing endless inmate appeals, steered the argument toward the strongest piece of evidence remaining against House: spatters of the victim's blood found on the defendant's jeans.
"I agree it would have been a much closer case," Scalia said, had the DNA results been available at trial. "But once a case has been tried ... we have a much different test. And that is whether any reasonable juror would have found him guilty. That is a very heavy burden."
In recent years, as scientific testing of biological materials left at crime scenes has improved, exonerations of death-row inmates have increased, raising concerns among civil libertarians and prosecutors that an innocent person could be executed, or already has been.
At House's trial, prosecutors argued that House lured Muncey from her home hoping to rape her. Her husband, Hubert, was not home and she was alone with their two children. Hubert Muncey had lied to his wife that night, telling her he would spend the night digging a grave. Instead, he went to a dance, according to court papers.
The Munceys' 10-year-old daughter testified that she was awakened in the night by a car horn. She also said she later heard a man with a low voice tell her mother that Hubert Muncey had been in a car accident.
Carolyn Muncey's body was found the next afternoon at the bottom of an embankment near her home. Shortly before her body was discovered, two witnesses claimed they saw House near the embankment, wiping his hands with a dark rag.
In seeking to prove his innocence 20 years later, House alleges that Muncey was probably killed by her husband. House's lawyers said they have several witnesses — who did not come forward or were ignored by police at the time of the crime — who now say Hubert Muncey abused his wife and confessed to killing her.
The lower courts discounted the new testimony, saying it was not credible because it was offered so many years later.
House's lawyer, Stephen Kissinger, sparred with Scalia over the defense's new theory that Muncey's blood did not get on House's pants during the killing. Kissinger argued the blood was spilled during testing by law enforcement authorities.
In court filings, Tennessee's lawyers said House's evidence and arguments are "of the type that juries hear and reject every day in criminal courts across the country." The state said House "must do more" by showing that his case is extraordinary because he is "actually innocent" beyond a reasonable doubt, the highest legal standard of proof.
Urging the high court to side with Tennessee, several states — including California, Florida and Texas, among the leaders in executions — told the justices in a friend-of-the-court brief that the criminal justice system is "not foolproof." Mistakes will be made, they said.
New Jersey lawmakers, on the other hand, voted Monday to suspend executions while a task force studies the fairness and costs of imposing the death penalty. New Jersey would become the third state behind Illinois and Maryland to suspend executions, but the first to do so through legislation. The others were done by executive order. Maryland has since lifted its suspension.
There are 10 inmates on New Jersey's death row. The state's last execution took place in 1963.