FEDERAL PROSECUTORS decided not to charge D.C. police officer Brian Trainer for the fatal shooting last year of an unarmed motorcyclist, concluding that there was not enough evidence to show the officer used "unreasonable force." The judgment that there was no prosecutable crime doesn't mean the shooting was justified, nor does it absolve the officer of blame. That was made clear in the police department's scathing internal review of the shooting, which ought to result in this officer's never again being entrusted with the public's safety.

Police officials announced this month that a departmental review board had determined that the fatal shooting of Terrence Sterling on Sept. 11, 2016, was unjustified and that Mr. Trainer should be fired from the department. No details were released. But The Post's Keith L. Alexander and Peter Hermann obtained the report of the Use of Force Review Board showing that the officer and his partner violated various departmental policies as they pursued and attempted to arrest the 31-year-old Mr. Sterling in the early hours of Sept. 11, including a policy requiring permission to engage in a high-speed chase and a prohibition against firing at moving vehicles unless deadly force is being used against officers or someone else.

The review, which included a crash reconstruction report and police radio transmissions, contradicted Mr. Trainer's account of the events, concluding that his decision to shoot "was not in defense of his life, nor was it in defense of the lives of others." Had not the officers violated D.C. police regulations, Mr. Trainer would not have found himself in a position of fatally shooting the motorcyclist twice in his neck and back. Given that devastating finding, there is little wonder that Mr. Sterling's family feels that justice has not been done. It has filed a $50 million suit against the officers and the city.

Mr. Trainer has been on paid administrative leave, and if he challenges the recommendation, there will be a hearing adjudicated by a panel of senior police leaders. Such hearings are generally open to the public, but according to a police spokesman, the presiding officer has the option to close proceedings. If there is a hearing, it is important that it be open to allow for a full accounting of this troubling event.