The cardinal sin here is the subordination of facts to a “narrative” adopted by activists and by the media. To adopt a narrative about how all police are racist or all police lie about shootings would be as unjust as to adopt a narrative about how all young black men are violent. Instead of insisting on our cherished narrative, we should be calling for the rule of law—which applies for everyone.
The relevant historical precedent for this is the Boston Massacre of 1770, in which British troops killed five men in what Americans said was an unprovoked shooting. The Redcoats were unpopular and resented, in much the same way, presumably, that the police are resented in Ferguson. And the shootings certainly played into the emerging American narrative of our oppression by a far-off, tyrannical monarch.
Yet local Patriots made a point of giving the soldiers a scrupulously fair trial, and no less a person than John Adams took on the task of the defending them. Adams was second to none in his support for the cause of liberty, and he would practically invent the idea of American independence. But he knew that liberty required the rule of law, which meant that the British troops deserved a genuine attempt to tell their side of the story and prove that their actions were justified. In the end, several were acquitted and two were found guilty of manslaughter.