Transocean Ltd., the drilling company that owned the Deepwater Horizon oil rig and leased it to BP plc before the 2010 Gulf of Mexico spill, admitted to negligence and partial blame for the rig’s catastrophic explosion. The multibillion-dollar question facing the company was whether a judge in New Orleans would hold it grossly negligent in civil litigation brought by the U.S. Department of Justice and other claimants. Such a finding would allow private plaintiffs to seek staggering punitive damages from Transocean. And it would allow BP to wiggle out of agreements to indemnify Transocean from much broader environmental liabilities.

Transocean and its lead counsel, Brad Brian of Munger Tolles & Olson, had some reasons to be confident when the judge began a long bench trial to apportion blame for the Deepwater blowout in February 2013. The company had paid a much smaller penalty than BP in separate criminal litigation, lending credence to Transocean’s argument that BP, the rig’s operator, was most at fault. Still, with so many billions hanging on the judge’s ruling, this was a bet-the-company trial.