From Chicago to Rio, from Jamaica to Nigeria, gang violence is leaving an indelible mark on communities across the globe, leaving authorities at a loss for what to do about the epidemic of lawlessness among young men who see little hope in their futures. Certainly the global economic crisis has much to do with the rise in gang violence and influence, as young men of color in most of the affected countries see few options for gainful employment. In Chicago, among 400 murders that have occurred in 2012, an estimated 80 percent of them have been gang-related. The killing in...