NEW ORLEANS (AP) — A federal judge conducting a trial to assign fault for the nation’s worst offshore oil spill dismissed claims Wednesday against a BP contractor and a company that made a key safety device on the drilling rig that exploded in the Gulf of Mexico in 2010, triggering the catastrophe.

After plaintiffs’ attorneys rested their case Wednesday, U.S. District Judge Carl Barbier ruled there was no evidence that BP’s drilling fluids contractor M-I LLC made any decision that led to the blowout of BP’s Macondo well. Barbier dismissed all claims against M-I on the 15th day of the trial.

The judge also agreed to rule out punitive damages against Cameron International, the manufacturer of the blowout preventer on the ill-fated Deepwater Horizon rig, which was rocked by an explosion and fire that killed 11 workers and touched off the enormous spill.

“I have not heard or seen evidence that would in any way support a finding of gross negligence or willful misconduct on the part of Cameron,” Barbier said.

The judge was acting on requests by M-I and Cameron to have claims against them dismissed. The two Houston-based companies have been bit players at the trial, which has centered on the actions and decisions of employees of energy giant BP, rig owner Transocean Ltd. and cement contractor Halliburton.

M-I is a wholly owned subsidiary of oil field services firm Schlumberger. Two M-I employees, Gordon Jones and Blair Manuel, were among the 11 workers killed in the blast.

BP, Transocean and Halliburton made similar requests Wednesday for Barbier to dismiss gross negligence and punitive damage claims against them, but the judge said he wasn’t ready to rule on them at this stage of trial.

Barbier is hearing testimony without a jury. Barring a settlement, he could decide how much more money the companies owe for their roles in the disaster. BP could be on the hook for nearly $18 billion in penalties under the Clean Water Act if the judge finds that it acted with gross negligence.

After Barbier’s rulings, the trial’s fourth week continued with more testimony by witnesses for Transocean, whose chief had executive testified Tuesday. BP and Halliburton also will call their own witnesses later in the proceedings.

Barbier has heard testimony by more than a dozen witnesses called by the Justice Department and private attorneys for Gulf Coast residents and businesses. The plaintiffs’ lawyers rested Wednesday after their last witness, a former Halliburton laboratory manager, finished testifying.

Earlier Wednesday, well control expert Calvin Barnhill testified that he believes Deepwater Horizon rig workers “got ahead of themselves” as they tried to seal the Macondo well and prepared to move on to drilling a different well.

“They were ready to get through with this job,” said Barnhill, a witness for Transocean.

But Barnhill said he hasn’t seen any evidence that rig workers sacrificed safety in a rush to complete a job that was behind schedule and millions of dollars over budget.

Transocean president and CEO Steven Newman testified Tuesday that he believes his company’s employees on the rig should have done more to detect signs of trouble before the blowout. However, he said the Swiss-based drilling company didn’t identify any internal “management failures” that led to the disaster.