So wrote Justice Holmes.
Now some in Congress are talking about taxing the AIG bonuses at 100%. Unfortunately, that is almost surely unconstitutional. To begin with, it would amount to a bill of attainder--an ancient practice of punishing one or more individuals in a defined group without due process that is proscribed by the Constitution. Also the ex post facto clause, which forbids punishment for acts that were legal when committed. And there may be others as well.
Nice try. No cigar.