Thomas More: What would you do? Gut a great road through the law to get after the Devil?Roper: I’d cut down every law in England to do that!Thomas More: Oh? And when the last law was down, and the Devil turned round on you—where would you hide, Roper, the laws all being flat? This country’s planted thick with laws from coast to coast . . . and if you cut them down. . . d’you really think you could stand upright in the winds that would blow then? Yes, I’d give the Devil benefit of law, for my own safety’s sake.

Whenever I start to think it would be a good idea to ignore a law that I support, in order to produce a result that I would like, I think of this passage from A Man for All Seasons–Robert Bolt’s masterful play about Thomas More's refusal to endorse Henry VIII’s break with Rome. And I have been thinking a lot about Thomas More today as leading Democrats and civil rights leaders have been calling on Attorney General Eric Holder to bring federal civil rights charges against the newly acquitted George Zimmerman.

The thing is, I would kind of like to see this happen. As I wrote earlier, I felt unsatisfied by the verdict. I believe that George Zimmerman is morally responsible for the death of Treyvon Martin, and I think he should be punished for it. I also believe that he was motivated by racial bias when he shot an African-American teenager--and this is precisely the sort of thing that civil rights laws have been designed to address. A federal civil rights prosecution could address what I perceive to be an injustice that has made millions of people in America feel less secure.

But then there is that whole Double Jeopardy bit in the Fifth Amendment. You know, the part that says "no person shall … be subject for the same offence [sic] to be twice put in jeopardy of life or limb." This is not an afterthought. It is a core principle of American justice. The state gets one bite at the apple. Period. They can’t keep going back and trying to get the result that they want, no matter how obvious it seems to me and everybody else that they should.

Now, I do know stuff. I know that criminal law in America is an extremely complex enterprise, with multiple, overlapping jurisdictions and a dizzying array of possible charges. There is enough room in the system for a clever lawyer (and aren’t all lawyers clever?) to argue that this-and-that charge is different from that-and-this charge---and that, therefore, a post-acquittal federal civil rights trial isn’t really double jeopardy. The courts have been sympathetic to these arguments and have allowed such trials to occur for the past forty years. If George Zimmerman is subjected to civil rights prosecution, the federal government won’t technically be violating the Constitution as currently interpreted by the federal government. But isn't this the kind of prosecutorial maneuvering that progressives and civil libertarians are supposed to be against in the name of, you know, civil liberties?

If Zimmerman is prosecuted in a federal court on a charge like “depriving Treyvon Martin of his civil rights by killing him,” he will once again be forced to defend exactly the same actions that he has already been acquitted for. Many people, including me, would like to see this happen. But the Double Jeopardy clause exists so that the people can’t keep going back to the prosecutorial well until they get the result that they would like to see. And while contemporary prosecutors have found all kinds of ways around the spirit of Double Jeopardy, it is a principal that progressives should be defending every chance that they get.

The progressives and civil libertarians who are pushing for a federal trial are playing a very dangerous game. They are hoping that—just this once—they can set aside one of the Constitution’s core procedural protections, which they have fought very hard to protect, in order to achieve the justice that they feel has been denied. They are betting that they can make just this one tiny little deal with the Devil of Overzealous Prosecutorial Power without it coming back to haunt them.

But the thing about the devil is that he always gets his due.