I think Martin's got it right . . .

. . . Goldmans should fork over a pile of cash now. A big pile. It would be a mistake to impose punative tax on bonuses over a long period of time: the banks would just dance around that one - most easily by raising salaries.

But going after the bonus pools on a one-off basis? Why not try it? Martin's logic is sound.

For you geeks out there, this article from the BofE's Andrew Haldane puts it all in context:

" . . . the scale of intervention to support the banks in the UK, US and the euro-area during the current crisis . . . totals over $14 trillion or almost a quarter of global GDP. It dwarfs any previous state support of the banking system."