It is unconstitutional for a police offcier to stop and "spot check" a car merely because the driver looks or acts suspicious, the U.S. Court of Appeals ruled here yesteday.

Instead, the police officer must have an "articulable suspicion" that the driver had broken the law or is about to break the law, the federal court ruled.

The court set the new standard in reversing the conviction of a man who was stopped by the police while cruising slowly in a largely residential Southeast Washington neighborhood. After stopping the man because he appeared suspicious to them, the police found out he had an outstanding traffic warrant, searched him and found a revolver and a sawed-off shotgun.

"In short, this was a stop to discover evidence where no adequate grounds for suspicion existed," the court ruled.

The ruling by the District's federal court, which cited the "potential for abuse" by police officers when they have unfettered discretion to stop cars randomly for "spot checks" sets a different standard for police here as compared with police in other jurisdictions.

For example, the Fourth U.S. Circuit Court of Appeals that presides over Maryland and Virginia, has said that roving police patrols have complete discretion in stopping individual motorists.

Because of the differing opinions in varying jurisdictions and the wide scale effects of such a ruling, lawyers aware of the ruling said it would likely be appealed to the U.S. Supreme Court.

The 2-to-1 ruling by the Federal appellate court has produced an unusually strong dissent by Judge Malcolm R. Wilkey who rejected the majority's opinion. He indicated the findings of the majority were based on "hypertechnicalities which were for sometime in vogue . . . in search and seizure cases . . ."

Judge Wilkey said the majority judges were operating "with the great clarify of hindsight" and that the opinion "serves as a perfect example of why we shall never be able to solve one of our most pressing urban social problems" - crime.

"Laws on the books are only as effective as they can be effectively enforced, " Wilkey said.

In writing for himself and Judge J. Skelly Wright, Harold Leventhal said it was clearly unconstitutional for the police to stop a car merely because an officer had a "hunch" about the driver. Instead the officer should conterfering with police offices who are more clearly shows an intent to break the law, Leventhal added.

Leventhal acknowledge that the ruling "invites hyperbolic opposition" in the premise that the courts are interfering with police officers who are out stopping criminals.

"Doubtless more crimes would be solved if all persons were subject to unrestricted police authority to stop and identify," Leventhal said. "Why not, it might be argued, since the innocent will have nothing to hide? If one is not sensitive to the implications for an open society, no amount of comment can explicate.

He pointed out that the police department keeps records of persons it stops in "spot checks," and that the person who is stopped is inconvenienced, sometimes embarassed perplexed, and "even fraught with anxiety."

". . . Possibilites for police abuse are present in the unchecked power to make stops for asserted 'traffic' purposes," Leventhal added. One of the possibilities is that "assertedly 'random' stops will be used to harass where reasonable grounds for suspicion do not exist." he said.

Leventhal said the court recognizes the need to enforce motor vehicle codes, but said that need does not require authority for discretionary traffic stops.

"When articulable grounds for suspecting a violation are present, the police may still stop and question, "Leventhal added. In addition, Leventhal said he could envision a system of raodblocks or a "truly random" method of checking for motor vehicle violations that could pass legal muster.

"But the police cannot use 'spot check' as a talisman to justify stops," the judge said.

Wilkey said in his dissent that the ruling was another example of the need to do away with the "exclusionary rule" under which illegally seized evidence cannot be used against a defendant.

He said the police had a right to stop the car because the defendant was acting suspiciously and watching the officers through a rear view mirror, and that therefore the police had a right to search the car and find weapons thatwere used as evidence against the defendant, Kevin Montgomery.

"The officers here did what their training had taught them to do, they did in fact what any citizens exceptthe offender here would have had them to do, " Wilkey said.