The Supreme Court, acting in three criminal cases, yesterday upheld general limits on police powers imposed by the Warren court in the 1960s but substantially eased them in some circumstances.

The mixed rulings were a departure from the conservative majority's generally consistent drive to cut back on the protections for defendants established by the liberal Warren court.

In one case, the court ruled unanimously that police in Virginia could not force a suspect to undergo surgery for the removal of a bullet sought as evidence because it might endanger his life or health and therefore was an unreasonable search.

In another, it said police in Florida must have an arrest warrant, probable cause or consent from a suspect before they can take him from his home to the police station even if the trip is only to obtain his fingerprints. But the majority added that such requirements would not be needed if police stopped suspects on the street and had fingerprint equipment at the ready.

In a third criminal case, the court expanded police powers to hold suspects without formally arresting them while investigators look for evidence. The majority said a 1968 Warren court decision, Terry v. Ohio, imposed no absolute time limits on such detentions.

The Virginia case, Winston v. Lee, involved a man allegedly wounded by a Richmond store owner during a robbery attempt. Rudolph Lee Jr. was arrested by police eight blocks from the store but said he had been shot by two men who tried to rob him. The bullet was lodged under Lee's collarbone.

Police wanted to remove the bullet to see if it matched shells from the store owner's gun. Lower courts refused to grant permission for the surgery, which would require general anesthesia.

"A search for evidence of a crime may be unjustifiable if it endangers the life or health of the suspect," Justice William J. Brennan wrote for the court. Brennan, who wrote the 1966 Warren court decision requiring suspected drunken drivers to submit to a blood test for alcohol content, said the general anesthesia and surgery in this case "would be 'unreasonable' " under the Fourth Amendment's protection against unreasonable searches.

Brennan said the recovery of the bullet might help prove Lee's guilt, but the state had other means to make its case. He said Virginia authorities had not shown a "compelling need" for the evidence that would outweigh the Constitution's protections of "personal privacy and dignity against unwarranted intrusion by the state."

In the Florida case, Justice Byron R. White said Florida police violated a 1969 decision, written by Brennan, when they went to a burglary suspect's house without a warrant or probable cause and took him against his will to the police station for fingerprinting.

White said that such actions violated the suspect's rights under the Fourth Amendment. The fingerprints, White said, could not be used at trial. They were "the inadmissible fruits of an illegal detention."

White went further, however, to say that nothing in the ruling should be taken to mean that police need probable cause, a warrant or consent before they can stop a suspect on the streets and obtain fingerprints.

Brennan, joined by Justice Thurgood Marshall, agreed with the outcome of the case but objected to what they called the majority's "return ing to its regrettable assault on the Fourth Amendment by reaching beyond any issue properly before us" in order to let police know what steps they might legally take in other cases to obtain fingerprints. The case is Hayes v. Florida.

In the South Carolina case, U.S. v. Sharpe, Chief Justice Warren E. Burger said police, acting only on a "reasonable suspicion," may detain suspects for 20 minutes while they search for evidence.

The 1968 Terry decision upheld the power of police, if they suspect a crime has been or is about to be committed, to detain suspects briefly and "frisk" them for dangerous weapons.

Burger said Terry and later cases "create difficult line-drawing problems in distinguishing an investigative stop from an arrest." Burger said that "obviously, if an investigtive stop continues indefinitely, at some point it can no longer be justified as an investigative stop."

But Burger said prior cases "impose no rigid time limitation on Terry stops." Questions about the propriety of such stops, he said, should take into account not only time but also whether police "diligently pursued a means of investigation that was likely to confirm or dispel their suspicions quickly."

Brennan, in a lengthy dissent, said Burger improperly extended the 1968 ruling and "evaded the requirements" of adhering to earlier decisions.

"This breed of decisionmaking," Brennan said, "breaches faith with our high constitutional duty to prevent wholesale intrusions upon the personal security of our citizenry."