Police officers must have "probable cause" to detain a criminal suspect for questioning, and they violate the Constitution if they don't, the Supreme Court ruled 6 to 2 yesterday.

Officers can't bypass the require-of probable cause by informing the suspect of his so-called Miranda rights to have an attorney present, the court said.

Justice William J. Brennan Jr. wrote the opinion for the court, which resolved an important issue of criminal justice in a case from Rochester, N.Y.

The court declined to expand a 1968 ruling that provided the first exception to the guarantee of the Fourth Amendment that seizures of persons must be based on probable cause.

That ruling validated a brief "stop and frisk" for weapons - an action that, Brennan wrote, "did not fit comfortably within the traditional concept of an 'arrest.'" Yet even this type of swift action was regarded by the court as a "serious intrusion upon the sanctity of the person," Brennan recalled.

By contrast, he said, the Rochester case involved a much more serious "seizure."

The case began in 1971 with the killing of the proprietor of a pizza parlor during an attempted robbery.

An informant supplied a possible "lead implicating Irving J. Dunaway. But a detective who questioned the supposed source of the tip - a jail inmate awaiting trial for burglary - learned nothing that, in his judgement provided "enough information to get a warrant."

Nevertheless, the officer ordered other detectives to "pick up" Dunaway and "bring him in."

They took him into custody at a neighbor's house did not tell him he was under arrest. "He would have been physically restrained if he had attempted to leave," Brennan said.

The officers drove the suspect to police headquarters, placed him in an interrogation room and, after giving him the Miranda warnings intended to protect a suspect against self-incrimination, questioned him. He then waived his right to counsel.

Later, Dunaway made statements - one within an hour, a second and more complete one the next day - and drew sketches. Both the statements and the drawings incriminated him.

At his trial for attempted robbery and felony murder, the judge denied Dunaway's motions to suppress the statements and sketches, and he was convicted. The conviction was upheld by the New York Court of Appeals but it was reversed yesterday.

"There can be little doubt that [Dunaway] was 'seized' in the Fourth Amendment sense when he was taken involuntarily to the police station," Brennan said. Even the state concedes that the police lacked probably cause for a formal arrest before Dunaway incriminated himself, he noted.

The decision rejected the state's contention that the seizure did not amount to an arrest and was permissible because police had a "reasonable suspicion" that Dunaway had "intimate knowledge about a serious and unsolved crime."

In the dissenting opinion, Justice William H. Rehnquist agreed that the detectives lacked "that degree of suspicion or probable cause that would have justified them in physically compelling [Dunaway] to accompany them to the police station for questioning."

But, he said, "I do not believe that the record demonstrates as a fact that this is what happened. No involuntary detention for questioning was shown to have taken place." Chief Justice Warren E. Burger signed the opinion, Justice Lewis F. Powell Jr. did not participate.