There is lots of fault to go around. BP, RIG, HAL, lack of government over site. But what people don't realize is the real cause of the disaster is the quantity of oil and pressure it was under are so much more that anyone thought. This is the mother load of all oil finds. I don't thinks they will ever stop the oil (relieve wells won't work) but I do think they will capture 100% of the oil within a month and the revenues for BP will be huge and the US deficits will be reduce. More oil than in the middle east!
What would make more sense would be to say that 700 million of the cleanup will likely be covered by insurance. Aside from that there is lots of evidence and eye witness accounts of engligence. You could also say that Transocean will share in the negligence. The biggest hit to BP will be to the brand.