After a Florida jury acquitted George Zimmerman in the death of Trayvon Martin on Saturday, President Obama appealed for calm. "I know this case has elicited strong passions," he said. "And in the wake of the verdict, I know those passions may be running even higher. But we are a nation of laws, and a jury has spoken." Although Obama wants us to respect the jury's verdict, writes Senior Editor Jacob Sullum, that does not necessarily mean he will. The Justice Department is mulling the possibility of prosecuting Zimmerman again, most likely based on the federal hate crime statute. Sullum says that would be wrong for at least four reasons.