well llegally you are correct but if I drive down thew road in my car and the garage that fixed it did a poor job or the replacement part broke and I crash it would seem to mitigate my culpability in the actual accident /event – even though I would be claimed against and liable.
They should also look at the contractors here and the part that failed
In the case of your car crash, if it was caused solely by the broken part and you'd have reasonably expected the garage to have done their job properly then you wouldn't be to blame at all, and could pass on all of the liability to the garage (though you might have to sue them to recover what you have to pay out).
In a similar way, it all depends what checks BP could have been expected to carry out. If they did everything reasonable to keep tabs on their contractors and the contractor didn't do the job properly but kept it quiet from BP then ISTM BP should be able to pass on all of their liability. In reality I don't think it's that clear cut, but neither were BP totally negligent in their checks so the contractor is only partly to blame.
Of course the contractor is a wholly US company without a name which used to include the word "British", so they're not so convenient a target.
To come back to the original point, if it wasn't that this has now just reduced to a political points scoring exercise, it's surely in the best interests of all involved that the CEO does the best possible job, which IMHO will happen if he's allowed a bit of time off to relax. Personally I think Obama comes out of this looking far worse – have now lost a lot of respect for him – though obviously I'm not part of the audience he's playing to.
