A fable attributed to Aesop speaks of a monkey who "induces a cat by flattery to extract roasting chestnuts from the fire. After the cat has done so, burning its paws in the process, the monkey makes off with the chestnuts and leaves the cat with nothing." Why is the above quote found in footnote one of the Supreme Court's March 1 decision in Staub v. Proctor Hospital ? It is there because the Supreme Court has now adopted the "cat's paw" theory of liability in an employment discrimination case. The term "cat's paw" has been used within employment law to describe a scenario where a decisionmaker acts as the "dupe" of another person, who has an unlawfully biased motive.

Staub brought suit pursuant to the Uniformed Services Employment and Reemployment Rights Act ("USERRA"). He had been an employee of Proctor Hospital and an Army reservist. After being fired in 2004, he sued, claiming his supervisors' hostility toward his military obligations resulted in his unfair (and unlawful) termination. Staub claimed his lower-level supervisors had made biased comments against him and one had issued an unfair corrective action. The ultimate decisionmaker was not among those Staub claimed were biased against him, but made his decision after receiving a report (from the issuing supervisor) that Staub violated the allegedly biased corrective action. Staub won a jury verdict against the hospital, but the case was overturned on appeal to the Seventh Circuit.

The Supreme Court reversed and remanded the case. The Court found that the earlier actions of Staub's lower-level supervisors set the wheels in motion to create liability for the employer, even though those lower-level supervisors did not make the decision to fire him. The Court held: "[I]f a supervisor performs an act motivated by antimilitary animus that is intended by the supervisor to cause an adverse employment action, and if that act is a proximate cause of the ultimate employment action, then the employer is liable under USERRA." The Court rejected the theory that "cat's paw" liability should be limited to cases where the decision results from the "singular influence" of, and "blind reliance" upon, the biased non-decisionmaker. Instead, the Court adopted a proximate cause standard.

In its reasoning, the Court followed principles of general tort law and agency to find liability. The Court found the employer was at fault because "one of its agents committed an action based on discriminatory animus that was intended to cause, and did in fact cause, an adverse employment decision." The Court also noted that USERRA contains language that is "very similar to Title VII," thereby suggesting this decision could affect discrimination cases brought on the basis of race, sex, religion, and national origin. The opinion was authored by Justice Scalia, with whom five other Justices joined. Justice Alito filed a concurring opinion, based on different reasoning, in which Justice Thomas joined. Justice Kagan took no part in the decision.