You're liable? They capped you 
Obama bum-rapped you
A price illegal and steep
You want to drill shallow
The Feds don't allow, no!
They say, you gotta go deep 
Though they've all decried you
That depth, fix has ne'er been tried 
Press takes you for a ride
And us, realizing:
Gov: All tar(p)-balls! 
 A long time ago, in an effort to encourage "energy independence" by increasing drilling in the US to reduce dependence on foreign oil, etc., a bill was passed by a bipartisan Congress and POTUS, "capping" (ouch) the liability of an oil driller at $75 million for any one incident. Whether the oil companies supported such measure or played no part in it is irrelevant -- the US wanted "evergy independence", and only Congress can pass laws, and only the POTUS can sign them into effect, or be overridden by a super-majority in Congress.
Therefore, it was patently illegal for Obama to break our own laws, passed by our own politicians, and indeed, "shake down" BP for $20 billion, so he could look like he'd "kicked someone's ass" (his own words), rather than blame himself for the fact that *several nations and foreign oil companies* offered assistance in the form of ships, equipment, etc. immediately after the spill, but Mr. Messiah turned them down, sayiing that we* could take care of it ourselves, and if we couldn't, he'd go down there 58 days later and use his oratorical skills to convince the well that "Yes, You Can Cap Yourself" -- "Change If We Believe In It".
btw, the same pattern occurred in the nuclear power plant industry. But that's another story - or parody.
2) BP had first asked the State of Louisiana for a permit to drill a well in that State's coastal waters, at a depth of only *500* (five hundred) feet, (~150m), a depth at which there is much experience in drilling, maintenance, and repair. The State said OK.
Enter The Dragon** - the Federal Government, which, without any legal authority whatsoever (other than being the biggest kid on the block), overrode Louisiana's permit, asserted their authority over US coastal waters beyond the State limit, and forbade BP to drill on the Continental Shelf (the shallow ocean bottom that slopes down from most of the US coastline for a while, before dropping off like a cliff into the deep blue).
Why? Because if there were an accident, a well that close to shore might foul the beaches!
(waits for raucus laughter to die down.)
 So, you (BP) must drill much farther offshore, off the Continental Shelf, in water *5,000* (five thousand) feet (~1,500m) deep -- a depth at which there is no experience in the kind of major repair here, and very little, if any, experience, period.
Good thinking! Now, instead of a leak fouling only Louisiana's beaches, it can foul Florida's, Cuba's, Georgia's, Newfoundland's, England's, France's .....
Note that professional divers can easily go to the 500-foot depth level and perform welding and other underwater repairs, so any leak could have been fixed permanently in a matter of hours or days. However, no human can go to 5,000' except inside a bathyscape (small ultra-depth submarine), which isn't capable of doing repairs.
 Since "tar balls" has been punned upon endlessly in the mass-mediaocrity, threw in a little shot at TARP, the Big Bailout Plan. Hey, this doesn't make sense. AIG, Goldman Sachs, etc., show years of incomepetence, and, in some cases, deliberate and possibly criminal malice, and they get bailed out by the taxpayers. BP, very much wanting to gain honestly the oil under the Gulf, has an accident, and suddenly they're being crucified.... Go ahead, 'splain why the two situations are different. The economic fallout from the former is far worse than from the latter.
(Yes, the environmental fallout from this is worse. Doesn't change the question.)
In the meantime, Congress and POTUS continue to pass laws without thinking about the consequences, and, for that matter, lacking the knowlegdge even to predict the consequences. Any econoturtle could have told them the eventual result of liability-capping, and it just gets easier (and stupider) from there.
Who but TT would Tell The TruTh, unpopular though it be?
btw, I agree that BP is not without blame, but the point is that they were *forced* into this situation by the Feds. Yeah, they could've Just Said No -- No, thank you, Sirs, we do not care to drill there -- but they need the oil for their business and their stockholders, we need it for (halo light) Energy Independence (chorus of cherubs doing "Hallelujah"), and, of course, they were mislead into believing that their max liability would be only 75 mil. .... Which *may* have induced them to be a bit less careful than if their liability were unlimited, as it should have been, and a mistake could cost 20 or 50 billion.
It's all about the incentives, and the Feds set up the wrong incentives, as they usually do, though they don't realize it, because they have some other goal in mind. Unfortunately, reality always wins in the end.
And Fed policies foul TT's habiTaT.
* "What's this "we" stuff, White Man?" -- old Tonto-Lone Ranger joke.
** Movie that made Bruce Lee famous.