Solid, substantiated and legitimate reasons for firing someone almost always trump bias claims based on a few isolated slurs—even when the trash-talking comes from a supervisor.
Recent case: Sergei, of Russian origin, worked as a nurse until he was fired for allegedly violating rules for handling narcotics. A patient under Sergei’s care seemed to be using up a drip bag filled with narcotics faster than he should have. Supervisors suspected Sergei had done something wrong. He couldn’t explain his actions, and was fired after further investigation turned up past drug administration irregularities.
Sergei sued, alleging his boss had insulted Russians. He argued this was national-origin discrimination and the real reason he was fired.
The court didn’t buy it, especially since Sergei couldn’t counter the investigation’s findings. (Volochayev v. Sebelius, No. 11-2229, 4th Cir., 2013)