In Sims v. MVM, Inc., Case No. 11-14481 (decided Jan. 17, 2013), the United States Court of Appeals for the Eleventh Circuit addressed how to apply the “cat’s paw” theory of liability in an age discrimination case.

The “cat’s paw” theory works like this.  Supervisor A terminates an employee.  There is no evidence that Supervisor A had any discriminatory animus towards the employee.  However, Supervisor B, who allegedly had discriminatory animus, induced Supervisor A to terminate the employee.  Supervisor A allegedly acted as a mere “cat’s paw” to give effect to the discrimination animus of Supervisor B, making the employer liable for discrimination.

The Eleventh Circuit addressed what the employee was required to prove when asserting a “cat’s paw” theory of liability in an age discrimination case.  The employee contended that he needed to prove only that the discriminatory animus of a supervisor was a “motivating factor” in the adverse employment action.  The Eleventh Circuit disagreed and ruled that the supervisor’s discriminatory animus needed to be the “but for” cause of the adverse employment action.  It was not enough to show that the discriminatory animus was one of the causes of the adverse action; the employee needed to show that without that discriminatory animus, the adverse employment action would not have occurred.

The Sims decision sets a high threshold for plaintiffs in age discrimination cases relying on a “cat’s paw” theory.  It would not be enough for an employee to claim that age bias was only one of the factors that influenced the employer’s decision.