AP Yahoo News, "The decision is a victory for the drilling companies, which in the past had routinely won broad waivers from rules requiring detailed environmental studies. After the BP disaster, the Obama administration pledged it would require companies to complete environmental reviews before being allowed to drill for oil."
The companies still must comply with other revised policies and standards, such as the new safety rules and specific requirements for equipment like blowout preventers (the device that notoriously failed after the explosion that caused the BP spill).
But the companies nonetheless get to skirt the full environmental review Obama promised offshore drilling projects would have to face, and mostly due to political reasons: The administration has been under persistent pressure to ease up its stance on drilling from politicians in the Gulf and from the GOP in general.