ExxonMobil has been fined $236 million (£153.4m) for groundwater pollution in the US.
The New Hampshire Supreme Court made the decision after a trial which started in April 2013.
A New Hampshire jury found the oil company responsible for the presence of toxic compounds in the region’s drinking water.
Vic Sher, Co-Founder of Sher Leff, the law firm which worked on the case, said: “The Supreme Court’s decision confirms what was presented to the jury – that ExxonMobil knew of the risks associated with adding MTBE [Methyl Tertiary Butyl Ether] to gasoline and failed to warn the State or the EPA [Environment Protection Agency] about those dangers.
“It sends a clear message to companies that they are responsible for the environmental consequences of their business decisions.”