Yesterday, a panel of the Sixth Circuit announced its decision in Lewis v. Humboldt Acquisition Corp, an ADA case in which the court upheld the position of prior panels requiring an ADA plaintiff to establish that his or her disability was the “sole reason” motivating an adverse employment action. As Mark J. Chumley of the excellent Management Rights Blog noted yesterday, this puts the Sixth Circuit in the distinct minority of the appellate courts to consider the standard of proof on causation in an ADA case:

“Of the ten circuits to consider the causation issue, eight apply a 'motivating factor' (or 'substantial cause') test, under which a plaintiff must only show that a disability was a motivating factor of the adverse employment action.

However, the current law in the Sixth Circuit is that a plaintiff must show that his or her disability was the 'sole reason' for the adverse employment action; this is sometimes referred to as the 'solely' standard.”

The Lewis decision prompted Mark and I to consider the impact of the Supreme Court’s decision in Staub vs. Proctor Hospital – the so-called Cat’s Paw decision – on ADA cases in the Sixth Circuit. As we noted here, the Staub decision supports a finding of illegal discrimination when an otherwise unbiased adverse employment decision is influenced by a supervisor who acts with discriminatory motivation. In Staub, you will recall, the Supreme Court upheld the hospital’s liability under USERRA, where the human resources manager’s decision to terminate the plaintiff was based at least in part on information provided by supervisors who had demonstrated hostility to his military obligations as a U.S. Army reservist. The Staub decision hinged on the Supreme Court’s finding that liability arises under USERRA, like under Title VII, when discrimination is a “motivating factor” in an adverse employment decision. If, as Lewis requires, the standard of proof in the Sixth Circuit for ADA discrimination cases requires proof that the plaintiff’s disability status was the “sole reason” for the plaintiff’s termination (as opposed to merely a “motivating factor”) then the risk of Cat’s Paw liability is significantly reduced for employers in the Sixth Circuit (and as Mark points out, in the Tenth Circuit as well). Stay tuned; the conflict between the Circuit courts on the causation standard in ADA cases appears destined for either en banc review by the entire Sixth Circuit or review by the Supreme Court.