Peabody Coal Co. (Peabody) (defendant) entered into a contract with respondent Missouri Public Service Co. (Public Service) (plaintiff) to supply Public Service with coal. When Peabody’s costs escalated sharply, Peabody several times attempted to negotiate a higher price per ton of coal delivered under the contract, but negotiations were unsuccessful. Peabody refused to continue delivering coal. Though it had adequate coal supplies and the ability to perform the contract, Peabody argued that its non-performance was justified because excessive economic loss excused non-performance under the doctrine of commercial impracticability. Public Service elected to consider Peabody in anticipatory breach of the contract and brought suit to compel specific performance. The trial court ordered specific performance and Peabody appealed.