THAT D.C. POLICE officials are now taking a closer look at arrests before referring them to the U.S. attorney for prosecution is a good thing. That Executive Assistant Police Chief Terrance Gainer saw a need to require a second screening by watch commanders tells a more disturbing story. The change was prompted by a Washington Times report that showed that the U.S. attorney declined to prosecute 38 percent of the police force's 52,823 felony arrests brought over a five-year period ending last Dec. 31.

The numbers are disquieting. During that time, nearly 17,000 felony suspects placed under arrest and processed by District police were not charged but were let go. A smaller number -- 1,168 -- had their cases dropped before indictment. And the cases of nearly 2,000 arrested suspects were dismissed by the courts.

The reasons for the high dismissal rates vary according to who along the criminal justice spectrum is speaking. Police officers claim they're doing their job. They point to prosecutors who fail to have their cases ready for court on time, and who skim off the good cases and duck the tough marginal ones that might mar their conviction records.

Prosecutors, on the other hand, complain about their heavy workloads and about poor cases presented by police that reflect sloppy paperwork, inadmissible evidence, a lack of witnesses and flawed searches. Each side has a bad word to say about the clogged D.C. Superior Court system.

Playing the blame game won't solve the problem, however. As the Washington Times report notes, some felony suspects fortunate enough to have the charges against them dropped actually end up committing serious crimes once they get out of jail. Serious public safety consequences follow for a city in which felony suspects are allowed to escape prosecution.

Chief Gainer's response is the right one. He wants the department's senior officers to ensure that officers on the street have the necessary training and skills to make cases that won't get thrown out. He considers this a priority. The U.S. Attorney's Office and courts ought to adopt a similar pro-active attitude and fix the flaws in their areas of responsibility that might be contributing to the problem. Carelessly putting suspected felons back on the street is not the answer.