In Commercial Credit Claims v. Workmen's Compensation Appeal Board (Lancaster), 556 Pa. 325, 728 A.2d 902 (1999), the employer issued an NCP accepting liability for physical injuries sustained by the claimant. the employer subsequently filed a termination petition, alleging that the claimant had fully recovered from the work injury. During hearings on this petition, the employer's medical witness testified that the main component of the claimant's problem was a psychiatric problem; because the witness had not treated the claimant prior to the work injury, he offered no opinion as to whether the psychological problem was causally related to the work injury. The WCJ accepted this testimony as credible and denied the termination petition, concluding that, where the employer's expert raises the possibility that the claimant suffered from a psychological disability caused by the work injury, the expert's testimony is equivocal with regard to whether the claimant made a full and complete recovery. The Workers' Compensation Appeal Board (WCAB) affirmed, and this court affirmed the WCAB's decision. On further appeal, our supreme court reversed. The court first observed that section 407 of the Act, 77 P.S. 731, states that all NCPs shall be valid and binding unless modified or set aside as provided by the Act. The court then noted that section 413(a) of the Act, 77 P.S. 771-772, provides for modification of an NCP upon proof that the original NCP was in any material respect incorrect at the time it was issued or upon proof that the claimant's disability has increased, pursuant to a petition filed by either party. The court in Commercial Credit held that, because the claimant never sought to modify the NCP to include compensation for his psychological injuries, the employer only needed to show that the claimant's physical injuries had resolved in order to succeed on its termination petition. The court stated that, for the same reason, "the lower tribunals erred by failing to confine their analysis of employer's termination petition to whether the injuries set forth in the original NCP had been resolved." Id. at 332, 728 A.2d at 905. The court elaborated as follows: Although the conclusion that we reach today is plainly dictated by the relevant statutory provisions, we note also that sound considerations of policy militate heavily in favor of this conclusion. To impose a burden on an employer to "prove a negative" by establishing that the subsequently alleged injury bore no causal relationship to the work- related accident would be fundamentally unfair. Regardless of whether the employer had notice of the purported psychiatric injury at the time that the NCP was executed, and regardless of how much time elapsed before the psychiatric injury arguably manifested itself, the employer would have to prove the absence of any causal relationship between the psychiatric injury and the work-related accident. We will not strain the humanitarian goals underlying the Workmen's Compensation Act by holding that employees may remain perpetually eligible for compensation merely by alleging psychiatric injury at the eleventh hour and waiting to see whether the employer can adduce the requisite expert testimony to disprove a causal nexus. Id. at 332-33, 728 A.2d at 905.