No man or woman has been executed in New York since 1963; the court ruled in 2004 that elements of a 1995 law restoring the state's death penalty made it unconstitutional. That decision left it to the State Legislature to modify the law, and opposition to the death penalty among Assembly Democrats has nullified any such effort.

But the 2004 decision was closely split, 4 votes to 3, and two of the judges in the majority have since retired. They were replaced by one appointee each of former Gov. George E. Pataki, a strong advocate for the death penalty, and Gov. Eliot Spitzer, who supports capital punishment only under narrow circumstances, as in the case of terrorists and the killers of police officers.

As in any death penalty case, the debate before the Court of Appeals on Monday was lengthy and highly technical, touching on dozens of questions of law and as many different elements of Mr. Taylor's crimes and trial. But questioning from the judges focused most intently on the prosecution's argument that the court should revisit its own 2004 decision.

In that case, the defendant, Stephen LaValle, was sentenced to death for raping and murdering a Long Island schoolteacher. As required by law, a judge told the jurors that if they could not choose unanimously between a sentence of death and one of life without parole, he would impose a sentence that would make Mr. LaValle eligible for parole after 20 to 25 years.

The Court of Appeals ruled in June 2004 that such instructions could coerce deadlocked jurors to vote for the death penalty out of fear that a violent defendant might be released from prison.

Mindful of the court's ruling, the trial judge presiding over Mr. Taylor's case, Steven W. Fisher, told a jury that he would "almost certainly" impose consecutive terms totaling more than a century if the decision were left to him, and that Mr. Taylor would be ineligible for parole until every year was served. Mr. Taylor and an accomplice, Craig Godineaux, had forced seven people into a walk-in freezer; bound and gagged the workers, and forced them to kneel before shooting each in the head.

Two survived to testify at trial. (Mr. Godineaux, who is mildly retarded, pleaded guilty to murder and is serving a life sentence without parole.) Because of Justice Fisher's careful instructions, Queens prosecutors argued on Monday, the jurors could be confident that Mr. Taylor would not walk free whatever their decision, and had voted to impose the death penalty without fear.

Under questioning, prosecutors told the judges that upholding that sentence would not amount to reversing the court's previous decision but would merely clarify part of it. The existing death penalty law could be constitutional in Mr. Taylor's case, said Donna Aldea, an assistant district attorney, even if unconstitutional in others.

"There would be no appearance of impropriety if the court unanimously agrees that the final sentence in LaValle, in fact, went too far," said Ms. Aldea.

But defense lawyers argued that because the original law that reinstated the death penalty in the state in 1995 had been rendered unconstitutional, absent legislative amendments, any death sentence stemming from it was also unconstitutional. Mr. Taylor's sentence, they said, should be changed to life without parole.

The prosecution's reasoning drew sharp questioning from some judges, including Chief Judge Judith S. Kaye. Reversing even one portion of the court's decision, she said, was the equivalent of telling the Legislature, "We didn't mean it." She also described as "fighting words" language in the prosecution's brief suggesting that the court's decision in the LaValle case was "unnecessary, inappropriate, and incorrect."

Even Judge Robert S. Smith, who sided against the 2004 decision, noted that overturning the court's own precedent — and one set so recently — would be a "radical" step.