The Supreme Court ruled yesterday that police are absolutely prohibited from questioning criminal suspects outside the presence of their lawyers once the suspects have asked to speak with an attorney.

In a 6 to 2 decision that marked an extension of its 1966 Miranda ruling and will make it harder for police to obtain confessions, the court said that, even after those accused of crimes have spoken to a lawyer, police may not try to question them again without the lawyer there.

The decision was a "double surprise," in the words of one expert, because the court has been increasingly unsympathetic to the claims of criminal defendants in recent years and because Justice Anthony M. Kennedy, who wrote it, has been considered equally reluctant to expand defendants' rights.

The court threw out the murder conviction and death sentence of Robert Minnick, a Mississippi man who escaped from jail and, with an accomplice, murdered two men during a burglary. The court said Minnick's confession, taken after he had spoken two or three times with a lawyer, was obtained in violation of his Fifth Amendment right against compelled self-incrimination, even though his interrogators repeated the required Miranda warnings before questioning him again.

The court said in Miranda that the Fifth Amendment requires that criminal suspects be advised of their rights to remain silent and to consult with legal counsel. In a 1981 decision, Edwards v. Arizona, the court ruled that, when a person accused of a crime invokes his Miranda rights and requests an attorney, police immediately must stop questioning and may not resume interrogation "until counsel has been made available."

Yesterday's opinion by Kennedy said barring police from reinitiating interrogation after a lawyer has consulted with the suspect and departed was "an appropriate and necessary application" of the rule announced in Edwards.

"A single consultation with an attorney does not remove the suspect from persistent attempts by officials to persuade him to waive his rights or from the coercive pressures that accompany custody and that may increase as custody is prolonged," Kennedy said.

In recent years, the court has narrowed many of the landmark defendants' rights rulings from the era of Chief Justice Earl Warren, but yesterday's ruling represented a broad interpretration of Edwards and Miranda.

It prompted a biting dissent from Justice Antonin Scalia, joined by Chief Justice William H. Rehnquist, who accused the majority of inventing "a veritable fairyland castle of imagined constitutional restriction upon law enforcement."

The Bush administration, in a friend-of-the-court brief, had urged the justices not to adopt a bright-line rule that would exclude "voluntary, reliable confessions from evidence."

Yale Kamisar, a University of Michigan law professor, called the decision a "double surprise" -- because of the outcome and the author, Kennedy, who wrote a dissent in a 1988 case in which the court extended the Edwards rule to questioning about separate crimes. Kennedy "would have been the last person I expected to write the majority opinion coming out the way he did," Kamisar said.

"This is a pretty dramatic message that the court still takes Miranda quite seriously," he added.

In his dissent, Scalia said that, after criminal suspects have had the opportunity to speak to a lawyer, there is less risk that they will be tricked or browbeaten into confessing, and such questions could be dealt with on a case-by-case basis.

Yesterday's decision leaves police free to question suspects represented by legal counsel if such conversations are initiated by the suspect.

Justice David H. Souter, not confirmed when the case was argued, did not participate in Minnick v. Mississippi.

Minnick and another man escaped from the Clarke County, Miss., jail in 1986, where Minnick was serving time for robbery. They broke into a mobile home looking for guns and shot the homeowner and a friend.

Minnick was arrested in California and interrogated by FBI agents who gave him the Miranda warnings and stopped questioning when Minnick told them to "come back Monday when I have a lawyer." Minnick consulted with an attorney two or three times over the weekend, who instructed him not to answer questions.

On Monday, Minnick was told he would "have to talk" to the Clarke County deputy sheriff and, after being advised of his rights, told the sheriff about events at the mobile home, saying the other man shot one victim, then ordered Minnick at gunpoint to shoot the other man.

"What today's decision does is to assure that, once someone wants a lawyer, he will have a lawyer in a meaningful way, at the time and place that having a lawyer matters most," said Floyd Abrams, appointed to serve as Minnick's lawyer before the Supreme Court.

Mississippi authorities were not available for comment.