If the Iraqis are forced to sign The Oil Bill and my best quess is that will be the ONLY way to get Bush/Cheney to consider an "end" to the "war", it should be a piece of cake to tear up the contracts in international courts once we have pulled out.
But that's the rub. Cheney's interpretation of withdrawal (and too many in Congress agree with him) will still leave a strongarm force of upwards of 50,000 US troops on 14 bases in Iraq.
So, try this out for a semi-baseless (sorry 'bout the pun. unavoidable) conspiracy theory: Those bases we built, at a staggering cost, in the billion$ per base, are not going to be handed over, even if Bush and Cheney are impeached and ALL of the United States Armed Forces personel are withdrawn. How is that possible? you ask.
A Corporate occupation force, 125,000 strong, working for Oil industry support services companies, Blackwater, KBR, et cetera, funded, at least initially, by the 8 billion$ pallets of $100 bills that went "Missing". Just like the other 40 billion$ unaccounted for in Iraq.
Hellisburnin's HQ is safely out of reach of US justice, Bush and family have a mountain fortress ranch of 98,000 acres in Paraguay and Cheney will probably be very comfortable in Dubai. The US will no longer be officially involved in Iraq (aside from reconstruction, we hope) but the junta will continue to plunder Iraq for years to come acting in the private sector.
I hope I'm wrong.