The Supreme Court ruled yesterday that prison and jail guards can be sued for heavy punitive damages for allowing rapes and assaults of inmates.

The 5-to-4 decision gives prisoners an important new weapon to deter what is generally considered a standard part of life in many institutions: constant exposure to rape and assault.

The court made the weapon more potent by ruling that the officials are subject to punitive damages not only when they purposely expose an inmate to an assault--by intentionally putting him in a cell with a known rapist, for example--but also when they act with indifference or with recklessness in a way that results in an assault.

The ruling has major implications beyond prisons because it applies to misconduct by any government official--from police officers to zoning commissioners--who can be sued for violating constitutional rights under the Civil Rights Act of 1871.

It was the first time the court has held squarely that punitive damage awards can be made under that widely used act, and is a significant setback for state and local officials, who have complained that they are already swamped with such civil rights suits.

In a lengthy dissent, Justice William H. Rehnquist said the court's action will subject officials to "random" and "open-ended" suits. "When swift action is demanded," he said, "their thoughts likely will be on personal financial consequences" instead of on "their official duties."

The decision came amid the first of several criminal trials involving widespread rape in the Prince George's County Detention Center reported in a series of Pulitizer Prize-winning articles last year in The Washington Post. While the ruling can have no impact on those trials, the inmates who were raped are free to use the ruling in future civil suits.

The ruling also might assist the plaintiffs in a continuing trial in federal court in Baltimore charging that three Prince George's police officials were part of a "death squad" that allegedly staged a series of holdups and burglaries in 1967 that resulted in two deaths and several injuries.

Daniel R. Wade, an inmate at the Algoa Reformatory in Missouri, brought yesterday's case against guard William H. Smith, who had placed in Wade's cell two inmates who later "harassed, beat and sexually assaulted" him, the court said.

Wade had a history of being assaulted by other inmates, according to the opinion, and one of those placed with him had a history of fighting. Wade said Smith made no effort to find out whether another cell was available.

After a jury found that Smith "knew or should have known" that an assault was likely under the circumstances, it assessed him $25,000 in compensatory damages and $5,000 in punitive damages. The 8th U.S. Circuit Court of Appeals upheld the award.

Punitive damages are imposed in lawsuits as an extra punishment or deterrent on top of damages that simply compensate a victim for actual losses. Generally, some extra showing of misconduct or malice is required for an award of punitive damages.

The issue before the court yesterday in Smith vs. Wade was whether punitive damages are available at all under Section 1983 of the civil rights law and, if so, how egregious the conduct must be to justify them.

Smith argued that only proof of intent to violate Wade's rights justified punitive damages. But Justice William J. Brennan Jr., writing for the court yesterday, said that no such proof has historically been required in most states for ordinary damage suits. He said he saw no evidence that Congress wanted a special standard created for civil rights suits.

Rehnquist, joined by Chief Justice Warren E. Burger and Justice Lewis F. Powell Jr., disagreed vehemently. In a lengthy dissent, Rehnquist said that "at least some degree of bad faith or improper motive" should be required, especially in civil rights cases "where the uncertainty resulting from largely random awards of punitive damages will have serious effects upon the performance by state and local officers of their official duties."

Justice Sandra D. O'Connor wrote a separate dissent, saying the ruling will "chill public officials in the performance of their duties . . . . "

In another decision yesterday, the court invalidated a lower court order barring the Los Angeles Police Department from indiscriminate use of the controversial and potentially fatal "choke hold." Police using that restraint, involving pressure on a neck artery, have killed 16 people in recent years in Los Angeles.

One victim who survived, Adolph Lyons, sued the LAPD under federal civil rights law, seeking damages and an injunction against use of the choke hold in the future. In a 5-to-4 ruling written by Justice Byron R. White, the court said Lyons could not seek the order because he could not show that police would ever again use the hold on him.

The decision in Los Angeles vs. Lyons was denounced by dissenting Justice Thurgood Marshall, joined by Justices Brennan, John Paul Stevens and Harry A. Blackmun. They said the decision was a sharp departure from prior court rulings and would make it impossible for federal courts to prevent future unconstitutional behavior by officials.