The House of Representatives has passed a 90 percent tax on the bonuses paid to AIG employees, seemingly forgetting President Obama’s admonition “that in a time of crisis, we cannot afford to govern out of anger, or yield to the politics of the moment.”

Everybody’s angry. But anger doesn’t make good law. And there are real questions about both the wisdom and the legality of such legislation. Bloggers like Conor Clarke, Megan McArdle, and Eugene Volokh have asked if the bonus tax is legal or constitutional. And thank goodness for bloggers who ask the questions that members of Congress and print journalists seem to ignore!

The bloggers wonder if after-the-fact taxes on specific people violate the constitutional ban on bills of attainder and ex post facto laws. (Ex post facto = after the fact.) Good questions indeed. But they should go further and ask, Are laws like this tyrannical? Ex post facto legislation isn’t just bad because it’s unconstitutional. It’s unconstitutional because it’s bad. (Nate Silver did raise these broader questions, arguing that the bonus tax bill was like the congressional intervention into the Terri Schiavo case: quite possibly legal and constitutional, but “it represented a gross overreach of the chamber’s authority, and ultimately undermined, at least a little bit, the rule of law.”)

Harvard law professor Laurence Tribe tells Conor Clarke, “It would not be terribly difficult to structure a tax, even one that approached a rate of 100%, levied on some or all of the bonuses already handed out (or to be handed out in the future) by AIG and other recipients of federal bailout funds so that the tax would survive bill of attainder clause challenge. …The fact that the individuals subject to the tax in its retroactive application would in principle be readily identifiable would not suffice to doom the tax either from a bill of attainder perspective or from a due process perspective.”

Which led liberal blogger Kevin Drum to this conclusion:

it looks like the answer here is simple: even though the purpose of this tax would pretty clearly be punitive with extreme prejudice, we need to carefully pretend that it’s not. And we need to make sure the legislative history shows that it’s not (it should be “manifestly regulatory and fiscal” Tribe says).

Considering that the rage of the anti-bonus army is being egged on by New York Post headlines such as “Not So Fast You Greedy Bastards” and “Tax the Damn Bonuses to Hell,” it might be tough to persuade a judge that this was “regulatory and fiscal,” not punitive, legislation.

The rule of law requires that like people be treated alike and that people know what the law is so that they can plan their lives in accord with the law. In this case, a law is being passed to impose taxes on a particular, politically unpopular group. That is a tyrannical abuse of Congress’s powers. And in addition, it is retroactive legislation, changing the law upon which AIG and its employees had relied. As James Madison wrote in Federalist 62, “It will be of little avail to the people, that the laws are made by men of their own choice, if the laws … undergo such incessant changes that no man, who knows what the law is to-day, can guess what it will be to-morrow.”

Selective taxation is tyranny. Ex post facto legislation violates the spirit of the liberal order, even if a particular piece of legislation can be “structured” to pass constitutional muster.