Burlington Indus., Inc. v. Ellerth, 524 U.S. 742, 761, 118 S.Ct. 2257, 141 L.Ed.2d 633 (1998), defined a "tangible employment action" as one entailing "a significant change in employment status, such as hiring, firing, failing to promote, reassignment with significantly different responsibilities, or a decision causing a significant change in benefits." Id. at 761, 118 S.Ct. 2257. The issue in Ellerth was the scope of an employer's liability for sexual harassment where the employer was not shown to be at fault. Id. As would be expected, the Court's analysis was concerned with agency principles, id. at 755, 118 S.Ct. 2257, and the opinion explicitly noted that the "tangible employment action" definition adopted therein was "for resolution of the vicarious liability issue...," id. at 761, 118 S.Ct. 2257. Accordingly, the Court held that proof of an adverse "tangible employment action" was relevant insofar as it would preclude an affirmative defense by an employer that the employee unreasonably failed to avoid or reduce the harm suffered. Id. at 765-66, 118 S.Ct. 2257.