If you believe that the end justifies the means, then you don't believe in Constitutional government. And, without Constitutional government, freedom cannot endure. There will always be a "crisis"-- which, as the president's chief of staff has said, cannot be allowed to "go to waste" as an opportunity to expand the government's power.
That power will of course not be confined to BP or to the particular period of crisis that gave rise to the use of that power, much less to the particular issues.
When Franklin D. Roosevelt arbitrarily took the United States off the gold standard, he cited a law passed during the First World War to prevent trading with the country's wartime enemies. But there was no war when FDR ended the gold standard's restrictions on the printing of money.
At about the same time, during the worldwide Great Depression, the German Reichstag passed a law "for the relief of the German people." That law gave Hitler dictatorial powers that were used for things going far beyond the relief of the German people-- indeed, powers that ultimately brought a rain of destruction down on the German people and on others.
If the agreement with BP was an isolated event, perhaps we might hope that it would not be a precedent. But there is nothing isolated about it.
The man appointed by President Obama to dispense BP's money as the administration sees fit, to whomever it sees fit, is only the latest in a long line of presidentially appointed "czars" controlling different parts of the economy, without even having to be confirmed by the Senate, as Cabinet members are.
Those who cannot see beyond the immediate events to the issues of arbitrary power-- versus the rule of law and the preservation of freedom-- are the "useful idiots" of our time. But useful to whom?