President Obama has called on the nation to accept the decision of the Ferguson grand jury. But looking forward, across much of this country, our system for dealing with police use of deadly force is broken. Police shoot and kill civilians at a rate unheard of in many other advanced nations, and even after incidents where there are indications that excessive force was used, police across many parts of the country seldom face trial or even dismissal from the force. A system for review of police misconduct must take care to vindicate and protect the innocent cop, but it also needs to deliver a credible promise of justice to the communities being policed. As a front-line means of regulating lethal force, grand juries -- which are secret, remote from the truth-finding of an adversary process, and dependent on prosecutors' guidance -- do not command broad public confidence. We see that in Ferguson today.