98 S.Ct. 2943, 2949, 57 L.Ed.2d 957 (1978) (citation omitted). If, however, defendant challenges causation either by introducing evidence of no causal link or of other cause, the burden on the plaintiff to show causation to establish her case is that “but for” the protected activity no action would have taken place. See McDonald v. Santa Fe Trail Transportation Co., 427 U.S. 273, 282 n.10, 96 S.Ct. 2574, 2580 n.10, 49 L.Ed.2d 493 (1976). Additionally, McDonneil-Dougias offers some possible methods of proof of pretext and describes what is meant by “pretext.” McDonnell-Douglas, 411 U.S. at 804-05, 93 S.Ct. at 1825-1826. Pretext is further defined in McDonald v. Santa Fe Trail Transportation Company, 427 U.S. 273, 96 S.Ct. 2574, 49 L.Ed.2d 493 (1976), as a “but for” standard .Cir.1980) (<HOLDING>). This analysis allows for the occurrence of
holding petitioner has the burden of proof under the strickland test holding that even if plaintiff could demonstrate that failed drug test proffered by defendant as ground for dismissal was in error that showing would not demonstrate that reliance on test was pretext for discrimination holding that in a mixed motive retaliation case the but for test applies to pretext but further holding that the burden shifts after employee has shown pretext under the but for test to the employer to show that absent retaliation the plaintiff would have lost his job anyway holding that pretext is subject to the clearly erroneous standard holding that the but for test applied in a mixed motive case under the national labor relations act