As a kid, when I got up in the morning, there was no more welcome a sight than a box of donuts on the kitchen table. Of course, I liked to eat donuts, but that was not the reason I welcomed their arrival. No, what the donuts told me was that while I was sleeping, my father had arrived home safely. My father was a police officer in Newark, New Jersey, a city in which bad things routinely happen to good cops. As South Carolina police officer Michael Slager has learned the hard way, today, bad things can happen to...