It is estimated that close to 5 million barrels of oil leaked into the Gulf after the Deepwater Horizon drilling rig explosion, April 20.

Defendants named in this action are BP Exploration & Production Inc.; Anadarko Exploration & Production LP; Anadarko Petroleum Corporation; MOEX Offshore 2007 LLC; Triton Asset Leasing GmbH; Transocean Holdings LLC; Transocean Offshore Deepwater Drilling Inc.; Transocean Deepwater Inc.; and QBE Underwriting Ltd., Lloyd's Syndicate 1036.

The Complaint maintains that the uncontrolled Macondo Well event on April 20, 2010 and uncontrolled blowout of oil and methane gas were not prevented by the defendants. In violation of federal regulations, each defendant (other than the QBE Lloyd's syndicate) failed to take necessary precautions to keep the Macondo Well under control.

For QBE, the complaint notes that because QBE Underwriting Ltd., Lloyd's Syndicate 1036 has provided evidence of financial responsibility and certain guarantees pertaining to one or more of the Transocean Defendants and Deepwater Horizon,the U.S. may bring this action directly against the Lloyd's syndicate.

For the other defendants, the complaint state they caused and/or contributed to the Deepwater Horizon Spill by failing to assure control of the Macondo Well through actions, corporate actions, and/or corporate practices of disregarding federal regulations, as evidenced by various safety and other audits of Deepwater Horizon, according to the complaint.

The amount of damages and the extent of injuries sustained by the United States, including to natural resources and wildlife, as a result of the Deepwater Horizon Spill are not yet fully known, but far exceed $75 million, the complaint says.

In a separate action, ACE American Insurance Company filed a complaint in the U.S. District Court Southern District of Texas, Houston division, against M-I, L.L.C.

The suit declares that no coverage exists under the ACE Policy for any claims against M-I arising out of the Deepwater Horizon Incident.

ACE said in the complaint that because BP is an additional insured under the ACE Policy, the Watercraft Exclusion operates to exclude coverage under the ACE policy for all losses arising out of the Deepwater Horizon Incident.

ACE maintains the Watercraft Exclusion does not apply to bodily injury or property damage arising out of the "ownership, maintenance, use or entrustment to others of any watercraft owned or operated by or rented or loaned to any insured. Use includes operation and loading and unloading."