ASSISTANT POLICE chief Maurice Turner, the man nominated to be the District's next police chief, says his goal in taking the job will be to lower the city's crime rate. Mayor Barry, who nominated Mr. Turner, says that he wants the next chief to be "someone whose single purpose would be to prevent crime. . . ." With the crime rate rising, the mayor and the nominee share a citywide concern. But every new police chief says he is out to stop crime. By saying so, he inevitably invites the public to make the crime rate the measure of his ability as chief. If the crime rate rises, the chief often points to "uncontrollable" factors, such as an influx of drugs or budget problems. If the crime rate drops, the police chief points to it as proof of his good work. But crime statistics are subject to various manipulations and interpretations that make them an unreliable measure of a police department or of a police chief.

The true measure of a good police chief is in the identity he creates for his department. This is particularly so in this city, where the police have a national role as protectors of the federal government and of the rights of people protesting against the government. An image of fairness and competence is also important for a police department in a city where there is a stark contrast between the people who have and the people who have not. The head of the D.C. police department must be trusted by all the people who live here. The chief must also be able to inspire trust inside the department to deal effectively with, say, disputes over promotion policy, pay raises, limits on manpower.

By suggesting increased use of foot patrols, Mr. Turner may be taking one step that could reduce crime. In looking for ways to fight crime, he should not forget that the police in this city have a unique commodity in their unusually good relations with the community. Police in many other cities would trade much to have the rapport that the District police share the people they serve. That good reputation can be lost much more easily that it was gained. Police abuses here were not addressed seriously until the 1970s, when chiefs Jerry Wilson and Maurice Cullinane demanded higher standards of behavior and brought more blacks and young people into the department.

In the end, any new chief will be judged by how quickly he acts to do what he can to contain crime, while vigilantly maintaining community perception that the police department cares. Judging by what this city has seen of Maurice Turner, he has the potential to handle it. The city council should move quickly to let him start the job.