The second half of a complicated civil trial began in New Orleans on Monday over the 2010 Deepwater Horizon rig explosion that killed 11 workers and spewed crude oil into the Gulf of Mexico for 87 agonizing days. The first half of the trial centered on whether BP, the rig’s owner, and its contractors were guilty of gross negligence causing the blowout of the well or only “simple” negligence, with less blame and, therefore, less punishment.

The trial judge, U.S. District Judge Carl J. Barbier, hasn’t ruled on the negligence charges yet, and in this second phase he will be asked to decide just how much oil flowed into the Gulf from the broken wellhead. There’s a lot at stake, not least of all the continuing recovery of the Gulf and those who rely on it for their livelihoods.

The Deepwater Horizon explosion and deluge of oil can rightly be labeled one of the worst industrial accidents to pollute the environment in the country’s history.

There’s a reason the government seeks big fines from polluters – wanton or otherwise. It’s to prevent future such disasters. BP’s long days in court should be a cautionary tale for every other oil company operating here.