The Supreme Court of the US state of New Hampshire has upheld the $236 million jury verdict in favor of the state against ExxonMobil, as the last holdout in proceedings against several companies for polluting groundwater with MTBE.

In April 2013, following what local media said was the longest trial in state court history, a jury found ExxonMobil responsible for the widespread presence of the gasoline additive in the state's drinking water.

In particular, the Supreme Court's decision upheld the jury’s allocation to ExxonMobil of 28.94% of the total $816 million verdict, based on its total share of MTBE gasoline distributed in the state. All the other companies settled either before or during trial.

A spokesman for a law firm acting as co-prosecutor with the state attorney general’s office said the Supreme Court's decision confirms what was presented to the jury – that ExxonMobil knew of the risks associated with adding MTBE to gasoline and failed to warn the state or the US Environmental Protection Agency.

The jury found also that ExxonMobil disregarded warnings from its own environmental engineers not to use the chemical on a widespread basis because of its threat to the drinking water supply.