Marie DiFiore v. CSL Behring LLC, 879 F.3d 71

DiFiore was Director of Marketing at CSL Behring (2008–2012) and raised concerns about alleged off‑label marketing and related compliance issues after a promotion in 2011.
After complaining, she alleges multiple adverse actions: two warning letters, a poor mid‑year performance review, a credit‑card warning, deteriorating supervisor relations, removal from a committee/meetings, and placement on a Performance Improvement Plan (PIP); she resigned shortly after the PIP.
DiFiore sued under the False Claims Act (FCA) anti‑retaliation provision, 31 U.S.C. § 3730(h), and asserted a state‑law wrongful (constructive) discharge claim under Pennsylvania law.
The District Court granted summary judgment for CSL on the wrongful discharge claim (finding no constructive discharge) and barred DiFiore from treating constructive discharge as an FCA adverse action; the FCA retaliation claim proceeded to trial.
The District Court instructed the jury that FCA retaliation requires "but‑for" causation (protected activity must be the but‑for cause of adverse actions); the jury found for CSL. DiFiore appealed the causation instruction, the summary judgment on constructive discharge, and one other jury instruction.
The Third Circuit affirmed: it held FCA retaliation requires but‑for causation, upheld summary judgment on constructive discharge, and found the jury instructions adequate.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Causation standard for FCA retaliation: whether "because of" requires motivating‑factor or but‑for causation	DiFiore: FCA uses a motivating‑factor (mixed‑motive) standard (citing Hutchins)	CSL: FCA "because of" language requires but‑for causation under Supreme Court precedent	Held: but‑for causation required (Gross and Nassar control; Hutchins dictum not binding)
Constructive discharge / wrongful discharge (summary judgment)	DiFiore: working conditions and PIP made continued employment intolerable, supporting constructive discharge	CSL: conditions were not intolerable; DiFiore resigned voluntarily and did not exhaust alternatives or comply with PIP	Held: summary judgment for CSL affirmed; no constructive discharge as a matter of law
Whether constructive discharge could be considered an FCA adverse action	DiFiore: constructive discharge is a cognizable adverse action for FCA retaliation	CSL: constructive discharge not established and thus cannot be an adverse action here	Held: because constructive discharge failed, it could not be relied on as an adverse action in the FCA claim
Jury instruction specificity (listing four incidents)	DiFiore: highlighting four incidents may have misled jury to ignore other evidence (totality of circumstances)	CSL: court instructed to consider totality and noted the four incidents were “among other things”	Held: instruction adequate and not misleading; no abuse of discretion

Gross v. FBL Financial Services, 557 U.S. 167 (Sup. Ct.) ("because of" requires but‑for causation under ADEA)
Univ. of Tex. Southwestern Med. Ctr. v. Nassar, 133 S. Ct. 2517 (Sup. Ct.) (Title VII anti‑retaliation requires but‑for causation; distinguishes motivating‑factor for status discrimination)
Hutchins v. Wilentz, Goldman & Spitzer, 253 F.3d 176 (3d Cir.) (discussed motivating‑factor language in dictum in FCA context)
Clowes v. Allegheny Valley Hospital, 991 F.2d 1159 (3d Cir.) (close/overzealous supervision insufficient for constructive discharge)
Egan v. Delaware River Port Authority, 851 F.3d 263 (3d Cir.) (post‑Gross/Nassar analysis applying lessened causation where statute/regulation used different language)
Wiest v. Tyco Electronics Corp., 812 F.3d 319 (3d Cir.) (constructive discharge occurs when conditions would compel a reasonable person to resign)