Federal prosecutors had been seeking about USD 20 billion in damages for an estimated 4,16,300 liters of crude that seeped into the ocean near the Chevron well in November 2011.
The prosecutor's office said it had no immediate comment on the ruling announced yesterday.
Federal judge Raffaele Felice Pirro dismissed the case after Chevron agreed to pay the equivalent of about USD 150 million in "compensatory activities." He said Transocean had no responsibility for the spill.