The Supreme Court yesterday significantly expanded police authority to conduct warrantless searches inside cars, giving police almost blanket search-and-seizure authority when they stop an automobile in connection with a suspected crime.

The justices voted 6 to 3 that any container in an automobile may be searched, including private bags, suitcases and other personal closed items, so long as police believe it may hold evidence of the crime.

The decision actually cut back on constitutional protections previously extended by the court, which placed some private containers off limits to warrantless searches, and drew an unusually vigorous dissent.

The ruling "shows contempt" for guarantees against unreasonable search and seizure, Justice Thurgood Marshall declared from the bench. It "will have profound implications for the privacy of citizens traveling in automobiles."

The ruling, written by Justice John Paul Stevens, does appear to help clear up an area of the law more confusing for police and the lower courts than perhaps any other. Such searches are an area of crucial importance in prosecuting drug violations in particular.

Under current law, police may clearly conduct a warrantless search of a car, unlike a house or an office, on "probable cause" to believe it is carrying contraband. But when it came to various containers inside the car--briefcases, bags, satchels, footlockers--police complained that they had to draw numerous distinctions, in some instances based on what the container looked like or is conventionally used for.

Luggage, for example, has been held too private for a warrantless search. A clear plastic bag, in contrast, could be searched.

Yesterday's ruling in United States vs. Ross grew out of a local case in which District of Columbia police searched a suspected drug dealer's car and, without a warrant, opened a folded-over brown paper bag that contained heroin. The U.S. Court of Appeals here ruled that a warrant was required prior to the search.

Stevens reversed the paper bag ruling, saying that too many "nice distinctions" were being required of law enforcement authorities. They must "give way," he said, "to the interest in the prompt and efficient completion of the task at hand.

"The scope of a warrantless search of an automobile is not defined by the nature of the container," he said, but "by the object of the search and the places in which there is probable cause to believe that it may be found."

The case began in 1978, when District police acted on a tip that Albert Ross Jr. might be carrying narcotics in the trunk of his car. Without going to a magistrate to obtain a warrant, police found Ross and stopped his car.

Searching it, they opened the trunk and found a closed, brown "lunch-type" paper bag containing a number of glassine packets of what turned out to be heroin and a zippered red-leather pouch containing $3,200 in cash.

The entire U.S. Court of Appeals ultimately heard the case and, in one of its most contentious recent rulings, found the search of the bag unconstitutional based on prior Supreme Court holdings that such containers carried with them an "expectation of privacy."

Stevens noted that magistrates are entrusted with the discretion of whether to issue a warrant when one is sought by police. His ruling, he said, simply transfers that discretion to the police officer on the scene of the car stop.

The discretion, he said, "is no broader and no narrower than a magistrate could legitimately authorize by warrant. If probable cause justifies the search of a lawfully stopped vehicle, it justifies the search of every part of the vehicle and its contents that may conceal the object of the search."

Marshall, writing with Justice William J. Brennan Jr., accused Stevens of overlooking the whole distinction between a magistrate and a police officer.

A magistrate is "neutral" and "detached," he said.

A police officer "on the beat hardly satisfies these standards. . . . A closed paper bag, a tool box, a knapsack, a suitcase, and an attache case can alike be searched without the protection of the judgment of a neutral magistrate," Marshall said, "based only on the rarely disturbed decision of a police officer that he has probable cause to search for contraband in the vehicle."

Justice Byron White submitted a separate dissent, saying he agreed with much of Marshall's statement. Justices Harry A. Blackmun and Lewis F. Powell Jr. added separate statements saying they agreed with the majority ruling in order to bring order to the confusion surrounding automobile searches.

Yesterday's ruling reversed a plurality opinion the court issued just last year, on the last day of the 1981 court term. That decision, Robbins vs. California, was written by retired justice Potter Stewart.