Trayvon Martin is dead, George Zimmerman has been acquitted, and millions of people are outraged. Some politicians are demanding a second prosecution of Zimmerman, this time for hate crimes. Others are blaming the tragedy on “Stand Your Ground” laws, which they insist must be repealed. Many who saw the case as proof of racism in the criminal justice system see the verdict as further confirmation. Everywhere you look, people feel vindicated in their bitter assumptions. They want action. But that’s how Martin ended up dead. It’s how Zimmerman ended up with a bulletproof vest he might have to wear for...