Yesterday three white men from Mississippi, ranging in age from 18 to 20, pleaded guilty to federal hate crime charges in connection with the June 2011 murder of James C. Anderson, a black man whom they beat and ran over with a Ford F-250 pickup truck in a Jackson parking lot. Unlike, say, Dharun Ravi's webcam peeping, this was indisputably a hate crime: Deryl Dedmon, John A. Rice, and Dylan Butler admitted they made a habit of targeting black people for harassment and assault, attacking them with beer bottles and slingshots, among other things. On the night they killed Anderson, they attended a birthday party in Puckett, Mississippi, where they decided to drive into Jackson for another racist rampage. They picked Anderson, who was stuck in the lot after locking his keys in his car, because he seemed drunk and therefore easy pickings. This despicable crime would have been subject to severe penalties regardless of motive, and one might wonder not only whether imposing extra punishment for the defendants' racism is appropriate but whether it is even possible with a crime that is already punishable by life imprisonment or the death penalty. But I'd like to ask a different question: Why was this a federal case?

Mississippi, after all, has a law against murder; it even has its own hate crime statute. In fact, Dedmon, who drove the pickup truck over Anderson, was sentenced in state court on Wednesday to two life terms without the possibility of parole. (Anderson's family had asked that he not receive the death penalty.) For good measure, Dedmon is expected to receive an additional 50-year sentence in federal court. Announcing the federal guilty pleas yesterday, John Dowdy Jr., the U.S. attorney for the Southern District of Mississippi, praised "the swift and certain investigation by the Jackson Police Department," so evidently this was not a situation where the victim's family would have been denied justice because of local officials' apathy or inaction. Likewise, the 2009 federal law under which Dedmon, Rice, and Butler were charged is named after two murder victims, Matthew Shepard and James Byrd, whose  killers were arrested, tried, convicted, and sentenced to life in prison or death, all without the benefit of hate crime laws, state or federal.

If the practical rationale for federal intervention in this case is hard to see, the constitutional justification is nearly invisible. The Matthew Shepard and James Byrd Jr. Hate Crimes Prevention Act loosened the requirements for federalizing such cases to the point that the Justice Department can prosecute essentially any violent crime if it believes the victim was selected "because of" his actual or perceived race, religion, national origin, gender, disability, sexual orientation, or gender identity. Whereas before the victim had to be involved in a "federally protected" activity (such as voting or education), now even the vaguest gesture toward the Commerce Clause will do, including a victim engaged in "economic activity," a "weapon that has traveled in interstate or foreign commerce," or a crime that "otherwise affects interstate or foreign commerce." The criteria are so loose that Dowdy did not even bother to mention interstate commerce (or any other federal nexus) in his indictment of Dedmon, Rice, and Butler. Let me help him out: The pickup truck was made outside of Mississippi.

Legislation like this makes a mockery of constitutional limits on federal authority, which emphatically does not include the power to prosecute violent crimes based on the perpetrator's bigoted motivation. And although the Supreme Court's doctrine of "dual sovereignty" says serial prosecutions for the same actions in state and federal court do not constitute double jeopardy, let's be honest: They do, and absurdly piling a 50-year sentence on top of two life terms is the least of the problems posed by that reality. The federal hate crime law means the Justice Department can (and does) prosecute people it believes were wrongly acquitted (or insufficiently punished) the first time around, a decision that is bound to be influenced by political considerations. Imagine what might happen, for instance, if a Florida jury acquits George Zimmerman in the death of Trayvon Martin because it accepts his self-defense claim. Would the Justice Department (which is already looking into the case) accept that result, or would it allege a racist motive and try, try again?