Giving credit where credit is due: argument preview for PPL Corp v Cmr

I've got a post up over at SCOTUSblog on the PPL Corp case, which involves the 1997 UK windfall tax imposed on energy companies that had been privatized under Thatcher--the US parent wanted to take a foreign tax credit for the tax but the IRS said it's not an income tax so no credit allowed. Yes, the year in question is 1997.  Fifteen years of litigation!  $$ at issue: $10M.  Who's got the better side of the argument: the Commissioner, in my view. The tax is a clawback to remedy a too-low flotation price, not a retroactive income tax. Oral arguments tomorrow, and I'll have a recap asap thereafter.