Nearly three years after a deadly rig explosion in the Gulf of Mexico triggered the United States' worst offshore oil spill, a federal judge in New Orleans is set to preside over a high-stakes trial for the raft of litigation spawned by the disaster.

Barring an 11th-hour settlement, US District Judge Carl Barbier was scheduled to hear several hours of opening statements on Monday by lawyers for the companies involved in the 2010 spill and the plaintiffs who sued them. And the judge, not a jury, ultimately could decide how much more money BP PLC and its partners on the ill-fated drilling project owe for their roles in the environmental catastrophe.

BP has said it already has racked up more than $24 billion in spill-related expenses and has estimated it will pay a total of $42 billion to fully resolve its liability for the disaster that killed 11 workers and spewed millions of gallons of oil.

But the trial attorneys for the federal government and Gulf states and private plaintiffs hope to convince the judge that the company is liable for much more.

With billions of dollars on the line, the companies and their courtroom adversaries have spared no expense in preparing for a trial that could last several months. Hundreds of attorneys have worked on the case, generating roughly 90 million pages of documents, logging nearly 9,000 docket entries and taking more than 300 depositions of witnesses who could testify at trial.

"In terms of sheer dollar amounts and public attention, this is one of the most complex and massive disputes ever faced by the courts," said Fordham University law professor Howard Erichson, an expert in complex litigation.

Barbier has promised he won't let the case drag on for years like the litigation over the 1989 Exxon Valdez spill, which still hasn't been completely resolved. He encouraged settlement talks that already have resolved billions of dollars in spill-related claims.

"Judge Barbier has managed the case actively and moved it along toward trial pretty quickly," Erichson said.

In December, Barbier gave final approval to a settlement between BP and Plaintiffs' Steering Committee lawyers representing Gulf Coast businesses and residents who claim the spill cost them money. BP estimates it will pay roughly $7.8 billion to resolve tens of thousands of these claims, but the deal does not have a cap.

Gross negligence

US prosecutors are determined to prove gross negligence caused the April 20, 2010, blast that killed 11 workers and sank the BP-leased Deepwater Horizon rig.

"Gross negligence is a very high bar that BP believes cannot be met in this case," BP group general counsel Rupert Bondy said.

"This was a tragic accident, resulting from multiple causes and involving multiple parties."

BP is also hoping to shift much of the blame - and cost - to rig operator Transocean and subcontractor Halliburton, which was responsible for a faulty cement job on board the offshore drilling platform.