British Petroleum and some of its subsidiaries failed to take precautions adequate to prevent the massive oil leak in the Gulf of Mexico this summer. Federal regulatory agencies failed to ensure such preventive measures were in place.
We already know that. Still, intensive probes into precisely what went wrong at the Deepwater Horizon drilling rig are important - and ought to focus not just on the past, but also the future.
Hearings on the disaster are being held by the Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement. Already some potential witnesses have refused to testify. At least one did so by invoking his Fifth Amendment rights.
Now there are questions concerning whether the investigative panel needs to ahere to formal rules of evidence, such as those used in federal courts. One concern is whether the possibility of criminal prosecution could discourage some witnesses from testifying. That would make it more difficult for the panel to get the truth.
Again, however, the basic facts are known. Just who was responsible for what errors - and possibly crimes - remains to be seen.
We do not believe the investigators should grant immunity to anyone. If crimes were committed, those responsible should be punished.
And, again, investigators should be asking whether specific lapses - both on the parts of drillers and government regulators - could occur again. If so, swift action should be taken to prevent another catastrophe. Promises, either by government officials or company representatives, are not enough.
What happened in the past is history. But whether it could happen again - and how to prevent it - are crucial questions the panel should address.