The Supreme Court yesterday gave cities broad powers to control adult movie theaters either by confining them to one area or dispersing them in order to "preserve the quality of urban life."

In a 7-to-2 decision, the court said the city of Renton, Wash., did not violate constitutional free-speech protections when it restricted adult theaters to a small, relatively isolated industrial area.

Renton's ordinance was not intended "to suppress the expression of unpopular views," Justice William H. Rehnquist wrote, but to "prevent crime, protect the city's retail trade and maintain property values"

The ruling in City of Renton v. Playtime Theatres Inc. extended and strengthened a 1976 ruling that said Detroit could disperse adult theaters if it wished. The effect of that ruling was limited because a majority of the nine-member court did not agree on a specific legal basis for it.

E. Barrett Prettyman, Renton's attorney, said yesterday's ruling gives cities a "clear signal that they can experiment rather broadly in this field with their ordinances."

Renton's city council, noting the problems that adult theaters had caused in other cities, passed the zoning ordinance in 1980 -- before any adult theaters had arrived in the city of 32,000 people a few miles south of Seattle.

A federal appeals court overturned the ordinance, saying that it may have been motivated by a desire to suppress speech and that the city needed to show that such a restriction on adult theaters was necessary to meet actual problems in Renton, not other places.

Rehnquist wrote in yesterday's opinion that the "First Amendment does not require a city, before enacting such an ordinance, to conduct new studies or produce evidence independent of that already generated by other cities, so long as whatever evidence the city relies upon is . . . relevant . . . . "

Playtime Theatres Inc., which acquired two theaters in Renton in 1982, said the city was in effect zoning adult theaters into oblivion because the small area set aside for them was mostly industrial park and already occupied by other businesses.

Rehnquist said that cities could not suppress or "greatly restrict access" to lawful speech, but "we have never suggested that the First Amendment compels the government to ensure that adult theaters . . . will be able to obtain sites at bargain prices."

Justice William J. Brennan Jr., joined by Justice Thurgood Marshall, dissented, calling the Renton ordinance "patently unconstitutional." Brennan said the city was discriminating against adult theaters simply because it did not like "the content" of the films shown in them.

The court majority, he said, was allowing the city "to conceal its illicit motives." Renton's ordinance "greatly restricts access to lawful speech and is plainly unconstitutional," Brennan said.

In another First Amendment ruling, the justices ruled 5 to 3 that California cannot require publicly regulated but privately owned utility companies to include information from consumer and other groups in their billing envelopes.

Justice Lewis F. Powell Jr., in an opinion joined by three justices, said the requirement violated a utility company's First Amendment rights "because it forces the company to associate with the views of other speakers and because it selects the other speakers on the basis of their viewpoints." The case is Pacific Gas & Electric Co. v. Public Utilities Commission of California.

The court also sharply limited the ability of defendants in some cases to argue that their convictions should be overturned because of improprieties during the grand jury investigation. Rehnquist, writing for the majority in U.S. v. Mechanik, Lill v. U.S. and Mechanik v. U.S., said the testimony of two federal agents together before the grand jury violated federal rules, but that the violation was a "harmless error" because the trial jury later found the defendants guilty.

Marshall dissented in this case.

And in a 5-to-4 ruling, the court expanded the ability of police to search automobiles stopped for traffic violations. Justice Sandra Day O'Connor said in New York v. Class that police could properly seize a handgun found after an officer entered a car to move some papers obscuring a vehicle identification number.