The Sixth Circuit Court of Appeals, sitting en banc, has decided that a worker suing under the Americans with Disabilities Act ("ADA") no longer must prove she was fired solely because of her disability, but instead need only show that her employer would have kept her "but for" her disability. Lewis v. Humboldt Acquisition Corporation, Inc.

Susan Lewis was employed as a registered nursed at Humboldt Acquisition Corporation, Inc., ("Humboldt") from July 2004 until March 20, 2006, at which time she was allegedly terminated for a profanity-laced outburst directed at her supervisors. Lewis filed a suit in federal district court for wrongful termination under the ADA. She claimed she was terminated because her medical condition made it difficult for her walk, and because she sometimes required a wheelchair.

Humboldt asked the court to instruct the jury that Lewis could only prevail on her ADA claim if her disability was the sole reason for her firing. Lewis, on the other hand, requested the court direct the jury to find in her favor if it found her disability was a motivating factor in her termination. The district court rejected Lewis’ instruction, following the longstanding 6th Circuit precedent that a worker suing under the ADA must prove she was fired solely because of her disability. The jury ruled in Humboldt’s favor.

Lewis first appealed to the 6th Circuit arguing the district court should have instructed the jury that her disability only had to be one motivating factor—the same test applied by most other federal circuits and applied in Title VII claims alleging discrimination based on race, color, religion, sex, and national origin. For the past 17 years, however, the 6th Circuit has required district courts to use the sole cause test. The Court first applied the "sole cause" requirement, as found in the Rehabilitation Act in a footnote in Maddox v. University of Tennessee, 62 F.3d 843 (6th Cir. 1995). The Court applied this reasoning since the ADA and the Rehabilitation Act paralleled each other.

The panel affirmed the district court’s judgment, holding: "this Court cannot overrule the decision of another panel . . . unless an inconsistent decision of the United States Supreme Court requires modification of the decision or this Court sitting en banc overrules the prior decision." Lewis v. Humboldt Acquisition Corp., No. 09-6381, Sixth Circuit Court of Appeals (March 17, 2011).

Lewis filed a subsequent appeal, and on Friday, May 25, 2012, the Court issued a 9-7 en banc decision, in which it abandoned the "sole cause" test, but also rejected the "motivating factor" test championed by the plaintiff. The Court instead concluded that the "but for" test espoused in Gross v. FBL Financial Services, 129 S.Ct. 2343 (2009), an age discrimination case, in which the U.S. Supreme Court held that employees suing for age discrimination under the ADEA must show they would have kept their jobs "but for" their age, because the statutory language in the ADEA requires proof that the individual was discriminated against "because of" his age. The 6th Circuit majority concluded the same test should be applied to disability claims under the ADA which similarly requires proof of discrimination "because of" the individual’s disability.

Because the Lewis jury was never given the opportunity to evaluate the evidence under the proper standard, the en banc decision remanded the case back to the district court for a new trial. Though employers in the Sixth Circuit have had the benefit of the "sole cause" standard for several years, the Sixth Circuit was alone among the other circuit courts in this interpretation of the ADA. Although the "but for" standard is more plaintiff friendly, it is certainly better than the "motivating factor" standard that the court could have imported over from Title VII.