[Doctor Stochastic]

...expressly forbad retroactive laws...

The Sherman Anti-Trust Act sort of quashed that idea. Learned Hand helped overthrow the concept when he held that such laws were ok.

[Bogolyubski]

I think it goes even further back. I recall from somewhere that a SCOTUS decision from 1798 or 1799 basically ruled that the ex-post-facto provision of the Constitution only pertained to criminal law, not civil law.