According to the Court:
Under a plain reading of the statute, and in accord with the position of other circuits, we conclude that the “sole causation” standard is not the appropriate standard for ADA claims. We hold that under a straightforward reading of the statute, the “motivating factor” test should be applied to ADA claims. This is consistent with the law of most other circuits,33 and it is in line with the causation standard we have applied to similar anti-discrimination statutes.
If there was any surprise in the decision for me it was that it had not been decided before.
Another interesting issue was how the Court came to decide it. The case is brought by an employee of the Department of Education under both §501 and §504 of the Rehabilitation Act. The question was whether the "sole" causation standard of §504 or the "motivating factor" standard of §501 was applicable.
Rather than just deciding that specific question, the Court first held that the §501 standard was the same as the ADA, and then resolved the previously undecided issue in the 5th Circuit. Such a departure from the conservative principle of only deciding the question before you may be what caused Judge Jones to concur only in the judgment.
It was also a good reminder to me that even though I don't do public sector work, I shouldn't ignore or read those decisions too hastily as they often have hidden gems applicable to the private sector when you would hardly expect it. Pinkerton is a case in point.