With “Bush derangement syndrome” having infected large swaths of the Left, it is no surprise that their fever dreams feature the prosecution of Bush Administration heavies for their “crimes against humanity” and the U.S. Constitution.

This weekend, the otherwise unremarkable Massachusetts School of Law at Andover will host a conference to that end. “This is not intended to be a mere discussion of violations of law that have occurred,” says dean Lawrence Velvel, but “a planning conference at which plans will be laid and necessary organizational structures set up, to pursue the guilty as long as necessary and, if need be, to the ends of the Earth.”

Even the Obama campaign has latched onto the idea, and that support has been a major sop for the hard-left disenchanted since the campaign began its pivot to the center for the general election.

Those planning up in Andover this weekend have a clear vision in mind. “For Bush, Richard Cheney, Donald Rumsfeld, and John Yoo to spend years in jail or go to the gallows for their crimes would be a powerful lesson to future American leaders,” says Velvel.

No doubt. But in today’s Wall Street Journal, Alan Derschowitz—no fan of the Bush Administration—considers what that lesson would be:

The real question is whether investigating one’s political opponents poses too great a risk of criminalizing policy differences — especially when these differences are highly emotional and contentious, as they are with regard to Iraq, terrorism and the like. The fear of being criminally prosecuted by one’s political adversaries has a chilling effect on creative policy making and implementation.

The heart of the problem is that the criminal law touches too much. As Dershowitz explains, “A politically appointed prosecutor, imbued with partisan zeal, could find technical violations of the criminal law in some of the envelope-pushing policies of virtually every administration.” He aptly quotes Stalin’s enforcer Lavrentiy Beria: “Show me the man and I’ll find you the crime.”

For those who do not inhabit the fever swamps, it should be obvious that prosecuting on the basis of policy difference–circumventing the impeachment mechanism put into the Constitution for just this purpose–would cripple the operation of government. And not just Iraq or other things one party or the other may dislike, but everything–guns, butter, and all.

Dershowitz suggests that prosecutions be limited to cases where “the criminal act and mens rea [guilty mind] are so apparent to everyone that no reasonable person would suspect partisanship.”

That’s good advice, but probably not enough at a time when the criminal law reaches so much ordinary conduct and increasingly lacks mens rea requirements. With around 4,500 possible federal offenses on the books, according to a recent study by Prof. John Baker, any prosecutor worth his salt could find something to charge. Really, the only thing to keep an Obama or McCain Administration from prosecuting is its own discretion–a weighing of the costs and benefits–and the fear that its officials might suffer the same fate someday.

The real lesson in this is not that we are all equal before the law (the common refrain among the hard-left as they daydream of sentencing Bush for his tax cuts) but that, under the criminal law today, a prosecutor can find a charge that would stick against anybody. It’s not just government officials making tough choices with life or death consequences who are at risk–we all are.