The state's lawyers say ExxonMobil and Citgo should pay $700 million in damages to monitor and clean up groundwater contamination caused by the gas additive MTBE — now banned in New Hampshire.
Lawyers for the oil companies say they have cleaned up their own sites and that contamination elsewhere was caused by third parties not named in the suit.
The jury trial started Monday and is expected to last four months. Judge Peter Fauver told jurors their service was appreciated, as the trial would be "an imposition on your lives."
More than 50,000 exhibits have been marked.