Cursory Constitutional Considerations on the AIG Bonuses

One of my roommates and I got to wondering about the constitutionality of any attempt to stop the AIG bonuses.

Potential problems:

1. Wouldn't it likely (but not necessarily) be a bill of attainder - legislation directed at one specific party?

2. Wouldn't it be an ex post facto law?

And if we're talking about state laws and you wanted to revive pre-1937 jurisprudence: