Amber Guyger’s killing of Botham Shem Jean is an unspeakable tragedy. It also highlights the need for officers like Guyger to face impartial justice. It is hard to think of a more tragic, more senseless shooting in America than the killing last week of Botham Shem Jean, a young black risk-assurance associate at PricewaterhouseCoopers, and a member of Dallas West Church of Christ. This is what we know so far. Jean was home alone in his apartment in the South Side Flats complexin Dallas when police officer Amber Guyger entered and shot him dead. The precise chain of events is...