Many people believe that violence is “caught” or “imported” into the United States’ borders from problems that start somewhere else—a phenomenon that I sometimes call contagion theory. To the contrary, our nation’s history shows that violence is embedded within our own legal, political and, yes, educational systems. This must end.

Many Americans just witnessed this in the militarized response to the mostly nonviolent protests of the killing of an unarmed young black man in Ferguson, Mo.