Oil giant Exxon Mobil has been ordered to pay damages to more than 10,000 petrol station owners for overcharging on the cost of its fuel.
The ruling by a federal court judge in Miami could set the US company back more than $1.3bn.
Exxon was told it would have to pay damages to dealers who bought supplies from it between 1983 and 1994.
A spokeswoman for Exxon, the world’s largest listed oil company, said it planned to appeal against the decision.
“We were seeking clarification on a number of legal issues that we thought were not resolved by the appeals process,” the spokeswoman said.
“Unless each dealer is required to prove damages, some dealers who were not damaged will receive money and we think that’s not right.”
Potential recoveries for some petrol station owners could reach more than $1m, one attorney said.
The suit against Exxon was filed in 1991. Exxon’s liabilities were established at trial in 2001, but payments were delayed while it appealed against the decision.
By the end of trading on the New York Stock Exchange on Friday, shares in Exxon Mobil were down 1.50% at $54.01.