The U.S. Court of Appeals yesterday ruled that D.C. police have the broad authority to ask pedestrians to produce identification even when there is no suspicion of criminal conduct. But at the same time, the court said it was concerned about some "disturbing" aspects of that procedure and strongly suggested some changes.

The appeals court left room for pedestrians who had sued the police department to try to prove at a trial that the department's policy of informally questioning people on the street is routinely carried out in violation of pedestrians' constitutional rights.

A lower court judge ruled last May that such informal "contacts" between police officers and citizens, thousands of which occur on city streets each year, violated constitutional protections against unreasonable searches and seizures.

Pedestrians who filed a class action lawsuit against the police department had complained that they were intimidated and harassed by such contacts with officers. They contended they were never told that they were free to simply refuse to answer and to walk away.

The appeals court yesterday rejected Senior Judge Edward M. Curran's conclusion that all such informal contacts and requests for identification by police automatically amount to an unconstitutional intrusion on privacy.

The judges, however, said they were concerned about evidence submitted in the case that showed some officers on occasion went beyond asking pedestrians a simple question when they approached them. The panel said they also found "other aspects of the contact practice disturbing."

The judges strongly recommended that in such informal circumstances, police clearly tell pedestrians they are free to leave if they desire to. They hinted that the department should review its policy of making a written record of all such informal contacts.

The judges expressed concern about the possibility that officers may be using a person's silence or refusal to cooperate as the sole basis for stopping them on the street.

"If an officer can detain a person, by force if necessary, simply because that person exercises his right to refuse to cooperate or answer questions, his freedom to walk away is indeed no freedom at all," the court said.

The appeals court returned the case to Curran to determine whether additional circumstances, such as a police officer's tone of voice, demeanor or the time and place of questioning, might transform "an otherwise inoffensive encounter" into an illegal restraint on a pedestrian.

If the facts in the case show "a pervasive pattern of such unconstitutional conduct," the appeals court said, Curran can then determine how to remedy the violations.

"They didn't throw us out of court, they merely sent us back for another go around," said Keith Watson, one of the attorneys representing the pedestrians.

The appeals court decision, written by Judge Edward Tamm, said every encounter with a citizen initiated by the police must be considered "in light of all the relevant facts and circumstances."

Tamm, who was joined in the decision by Judges J. Skelly Wright and Harry T. Edwards, noted that if a police request for identification were ruled an unconstitutional "seizure," that would prevent police from questioning potential witnesses to criminal activity or a person who appears to need help, and it would stop police from seeking voluntary help from citizens.

The test for whether such a seizure has occurred, the court said, "is whether a reasonable person, innocent of any crime, would have felt free to walk away under the circumstances."

The appeals court suggested that such subtle and controversial questions would be easier to answer if in the future police clearly informed citizens that they were free to leave and did not have to answer any questions or produce identification.

"In view of the persistent problems and continuing litigation police 'contacts' with citizens in the District of Columbia have caused, we strongly recommend that the police include this statement in its contact procedure and policy," the court said.

In sending the case back to the trial court, the appeals court judges noted that the pedestrians had already submitted evidence that some police-citizen contacts have gone well beyond "asking a simple question" and have raised serious questions about police conduct.

For example, the appeals court cited in a footnote one "contact" in which a police officer drew a gun and six to eight other officers arrived during a "contact" that lasted one half-hour.

In another case, a person was frisked and told he would be arrested if he continued running down the street and in another, that lasted two hours, a person was told not to leave and was warned that he could be taken to the police precinct.

In none of those cases was an arrest made.

"We've got lots of evidence to show that the police in general do abuse these contacts," said Arthur Spitzer, the legal director of the Washington office of the American Civil Liberties Union, which worked on the case.

"I think the court failed to recognize the true coercion that is really present in many if not most of these police-citizen contacts. But they have given us a chance to demonstrate that coercion at trial," Spitzer said.