If the Department or the employe establishes that within the 6 months prior to the alleged violation, the employe exercised a right provided in the act, the nonmanufacturing employer shall have the burden to show just cause for the employer's action by clear and convincing evidence in a proceeding brought under Chapter 321 (relating to enforcement procedures and penalties). For purposes of this section, just cause is substantial evidence that the employer's action would have been taken regardless of whether the employe exercised rights under the act.
34 Pa. Code § 319.3