In a 1995 attempt to encourage more exploration, Congress agreed to reduce the cut of the proceeds the government could collect on oil and gas drilling in deep waters. Ten years later, despite higher oil prices and declarations from President George W. Bush that more incentives were not needed, a Republican-led Congress reduced royalties yet again.

And in a sign of how money had influenced and distorted the debate, throughout the last decade the Louisiana Congressional delegation, for a time including the state’s current governor, Bobby Jindal, backed expanded offshore drilling so that Congress could use proceeds to pay for coastal damage caused by oil-and-gas operations. In 2006 the delegation supported legislation giving a share of federal royalties to states that allowed drilling in federal waters off their coasts, essentially using national revenue to encourage more exploration.

At the same time that Congress called for new drilling incentives, it also gutted oversight. From 2002 to 2008, legislators approved budgets reducing regulatory staffing levels by more than 15 percent  despite more complex deep-water operations and Interior Department concerns, voiced in 2000, that industry’s extensive use of contractors and inexperienced offshore workers posed new risks in deep water.

It’s not as if Congress didn’t know the risks. Its own research arm, which issues frequent spill-response readiness assessments, has repeatedly cited a 2004 Coast Guard study finding that its “oil spill response personnel did not appear to have even a basic knowledge of the equipment required to support salvage or spill clean-up operations.” Nevertheless, lawmakers failed to act aggressively to ensure adequate oversight.

To be fair, Congress wasn’t alone. The same criticism could be leveled at many environmental groups, which were far more interested in maintaining the exploration moratoriums in federal waters than in the safety of ongoing offshore activity. This focus on stopping new drilling  instead of on keeping the water clean  helped give Interior the space to cater to oil companies. As a result, regulatory proposals often received fewer than 10 public comments, mostly from industry, resulting in rules more favorable to it.