One of you asked a terrific question in class Wednesday: suppose the statute at issue in Plaut had simply created a much longer statute of limitations (or even eliminated it altogether), such that the plaintiffs in the dismissed actions could then file new law suits that would be timely. Would that violate the rule articulated by the Court in Plaut?
The short answer is yet. I went back and read the full opinion this morning, and the broader rationale clearly rests on the idea that once an action ends in a "final judgment" -- the final word from the judicial department -- Congress cannot disturb it without violating separation of powers principles.
How can this be squared with Wheeling Bridge II? The critical difference concerns the nature of the claim, especially with respect to time. In Plaut, the plaintiffs claimed that certain specific actions taken in the early 1980s violated the Securities Act. Those claims were litigated and finally resolved by the judiciary. And once the judiciary issues a final judgment, it cannot be disturbed. In contrast, the claim in Wheeling Bridge II concerned the legality of the bridge at the moment of the later law suit. Thus, Congress could not go back and somehow say that the Wheeling Bridge had always been legal. But it could say, by statute, that it is now legal. And once it is legal, the justification for ongoing relief -- the injunction -- dissolves.
One final point. Had Congress amended the statute of limitations before the judgment in Plaut's law suit had become final -- say, while his petition for certiorari at the Supreme Court was pending -- it would have been permissible for courts effectively to retroactively apply the new statute of limitations. That it, the principle announced in Plaut only applies to judgments that have become final. As Scalia explains, it is final judgments that are the final word from "the Article III hierarchy" of courts, and it is those that cannot be undone.
Hope this helps. And I'm happy to field more questions on the point.