NEW ORLEANS (AP) — BP has lost two big rulings in its fight to shield itself from potentially having to pay billions of dollars more in damages related to the worst offshore oil spill in U.S. history, though the company was able to limit some of its future exposure. 

A federal judge ruled Tuesday that BP PLC is not entitled to coverage for the spill under insurance policies totaling $750 million held by Transocean Ltd., owner of the Deepwater Horizon rig that BP was leasing at the time of last year's Gulf of Mexico disaster. 

"Because Transocean did not assume the oil pollution risks pertaining to the Deepwater Horizon Incident — BP did — Transocean was not required to name BP as an additional insured as to those risks," U.S. District Judge Carl Barbier wrote in his ruling. "Because there is no insurance obligation as to those risks, BP is not an 'insured' …. for those risks. Therefore, BP is not entitled to the declarations of coverage it seeks."