Thomas Hebden, a coal miner, was awarded workers’-compensation benefits for an occupationally acquired pulmonary disease known as coal-worker’s pneumoconiosis. Neither Hebden nor his employer appealed the award. Years later, Hebden’s employer filed an action with the Pennsylvania Workmen’s Compensation Appeal Board to terminate Hebden’s benefits, alleging that Hebden’s condition had changed and that he was no longer disabled and not entitled to any benefits. The referee and appeal board ruled for the employer. Notwithstanding conflicting expert testimony concluding that Hebden never had pneumoconiosis and that pneumoconiosis was not a disease, once contracted, you can recover from and that Hebden was still suffering from pneumoconiosis, a Pennsylvania trial court affirmed the appeal board’s decision. Hebden appealed and argued that the preclusion doctrines of res judicata (claim preclusion) and collateral estoppel (issue preclusion) barred his employer’s case to terminate his benefits.