Nobody west of the Hudson River believes that the bankers who ran their companies into the ground then rewarded their success with multi-million dollar bonuses should be allowed to keep the money.

Here's an easy way to get a lot of it back:  tax 'em. Tax the banksters. I mean serious, mortgage-the-yacht taxation. If Congress has the will (hah!) they can do it tomorrow.

Progressives need to know this fact:

The Supreme Court has never wavered from the proposition that it is perfectly okay for Congress to pass tax laws whose effect is retroactive. Sometimes, the period of retroactivity can be, and has been in some instances, years in the past.

That's not fair! you say. What about the ex post facto clause? What about 5th Amendment Due Process? Surely those taxpayers have relied on the tax laws as written, and arranged their lives accordingly?

The ex post facto clause refers to criminal laws; that is not at issue here. The "reliance" doctrine of modern contract law, (where if I incur sunk costs to prepare for your first shipment, and you decide not to send it, you're liable for my sunk costs even though I haven't paid you any money under the contract.) doesn't apply: taxation is not a contract, it's a law.

And the due process restriction holds, but under the lowest level of the Court's "scrutiny" of Congressional actions.

Here's the Supremes to sing for you, from U.S. v. Carlton (1994):

This Court repeatedly has upheld retroactive tax legislation against a due process challenge. Some of its decisions have stated that the validity of a retroactive tax provision under the Due Process Clause depends upon whether retroactive application is so harsh and oppressive as to transgress the constitutional limitation. The harsh and oppressive formulation, however, does not differ from the prohibition against arbitrary and irrational legislation that applies generally to enactments in the sphere of economic policy. The due process standard to be applied to tax statutes with retroactive effect, therefore, is the same as that generally applicable to retroactive economic legislation: * * * that burden is met simply by showing that the retroactive application of the legislation is itself justified by a rational legislative purpose.

(emphasis added)

and

Taxation is neither a penalty imposed on the taxpayer nor a liability which he assumes by contract. It is but a way of apportioning the cost of government among those who in some measure are privileged to enjoy its benefits and must bear its burdens. Since no citizen enjoys immunity from that burden, its retroactive imposition does not necessarily infringe due process * * *  (quoting Welch v. Henry, 305 U.S. 134, 146-147 (1938)).

U.S. v. Carlton, 512 U.S. 26 (1994)