The War on CopsViolent crime has been rising sharply in many American cities after two decades of decline. Homicides jumped nearly 17 percent in 2015 in the largest 50 cities, the biggest one year increase since 1993. The reason is what Heather Mac Donald first identified nationally as the "Ferguson effect": Since the 2014 police shooting death of Michael Brown in Ferguson, Missouri, officers have been backing off of proactive policing, and criminals are becoming