In an action of critical importance to highway safety and the auto industry, the Supreme Court yesterday let stand a decision that the government can order manufacturers to recall vehicles for correction of a safety-related defect without having to prove that the defect has caused, or will cause, a significant number of accidents, injuries or deaths.

The justices declined without comment a petition by General Motors Corp. to review the decision, which the U.S. Circuit Court of Appeals for the District of Columbia handed down in June. Friend-of-the-court briefs on behalf of GM were filed by Chrysler Corp., Volkswagen and the Automobile Importers of America.

The appellate court's five-sentence opinion upheld the contention of the National Highway Traffic Safety Administration that, under the 1974 amendments to the traffic safety law, the demonstrated failure of a component crucial to safety, such as brakes or lights, establishes an "unreasonable risk of accidents" -- even if there are no accident data to prove the risk.

The NHTSA, a unit of the Department of Transportation, claimed that proving the existence of every "unreasonable risk" with accident data would be impractical, partly because such data often are unavailable, incomplete or erroneous. In addition, the agency said, bringing into court all of the relevant witnesses -- including vehicle owners, their mechanics, and their doctors -- would create huge legal costs and problems.

GM argued that the appellate court had created "considerable uncertainty as to whether the existence of 'an unreasonable risk' . . . is a factual matter susceptible of trial, or a question to be resolved by judicial hunch and supposition without admission of evidence."

Congress intended that the agency order recalls only when safety considerations outweigh the costs of compliance, GM said.

The case at issue began when the Center for Auto Safety, a Washington-based nonprofit group, complained to the NHTSA that 1959 and 1960 Cadillacs were equipped with what GM conceded to be a defective pitman arm, a component of the steering system. If a pitman arm fails, the car can't be steered.

In September 1973, the agency ordered GM to recall the 1959-1960 Cadillacs still on the roads (43,400 of 284,456 produced) and to replace -- at its expense -- the pitman arms that were "subject to sudden and catostrophic failure" and thereby were creating "an unreasonable risk." GM immediately filed a suit to block the order.

At trial in U.S. District Court here, the manufacturer offered testimony to show that pitman arms, when they fail, nearly always do so only during low-speed maneuvers, in which full turns of the steering wheel put heavy stress on the arms.

The Cadillacs in question had traveled some 24 billion miles without "ducumented injury or death resulted from pitman arm failures," GM told Judge Oliver Gasch.

Ruling for GM, he held that the government had not carried the burden of showing, with a preponderance of the evidence, that pitman arms failed at high speeds and that the defect consequently was safety-related within the meaning of the law.

Reversing Gasch 2 to 1, the appellate court held that the government had been entitled to a summary judgment without a trial on whether a defect existed and whether it was safety-related.

The court said the evidence was "uncontradicted that General Motors sold six times as many replacement pitman arms (26,424) for the 1959-1960 Cadillac models as for adjacent model years, that steering pitman arm failures have occured while these models were being driven, and that, when the steering pitman arm fails, the driver loses control of the car."

The foregoing "uncontradicted facts demonstrate 'unreasonable risk of accident' stemming from the defect," the majority said.

The appeals court made a similar ruling for the government in a case involving fires in about 375,000 1965-1966 Chevrolets and Buicks equipped with faulty Rochester Quadrajet Carburetors.

GM admitted to at least 665 engine compartment fires; the government asserted that GM had reports of at least 293 more such fires, some of which spread of passenger compartments.