Retaliation for family leave

1. Whether the text of the FMLA, including 29 U.S.C. §2615 and §2617, requires plaintiffs to prove that exercise of rights under the FMLA was the but-for cause of an adverse employment action, or whether courts should defer to the Department of Labor’s lesser standard of causation in 29 C.F.R. §825.220(c). 2. Whether a court of appeals may refuse to decide, on waiver or forfeiture grounds, a purely legal challenge to circuit precedent when an intervening decision of this Court fundamentally alters the governing legal framework after trial but before appellate review, when raising the argument in the trial court was futile because it was foreclosed by binding circuit precedent, and when the issue was raised and fully briefed at the first non-futile opportunity on appeal.