Federal prosecutors can seek up to $40 million in damages against Fleet Management, the operator of the Cosco Busan boat which leaked thousands of gallons of oil into San Francisco Bay in 2007.
Fleet had offered to plead guilty when it expected fines to be limited to $215,000.
But a new indictment accused the company of causing $20 million in damage, leaving the company liable for up to double that in fines.
The regional appeals court declined to hear an appeal from the defense attorneys.
The company faces a separate trial on felony counts of obstructing justice by forging records.
Jackson West figures the paying for the cleanup is the least the company could do.