In the circumstances presented, the district court's use
of the phrase "substantial factor" rather than "motivating factor" was not
misleading and adequately informed the jury of the law. The words
"substantial" and "motivating" are reasonably interchangeable or at least
have considerable overlap. See Fields v. New York State Office of
Mental Retardation and Developmental Disabilities, 115 F.3d 116, 120-21
(2d Cir. 1997) (generally stating that plaintiff must prove prohibited
consideration was a "motivating factor" in employer's decision, but also
referring to "a substantial or a motivating factor" and "a substantial
motivating reason" (emphasis omitted)); Burger v. New York Inst. of Tech.,
94 F.3d 830, 833 (2d Cir. 1996) (requiring evidence sufficient to support
inference that impermissible motive was "a substantial factor");
Tyler v.
Bethlehem Steel Corp., 958 F.2d 1176, 1181 (2d Cir. 1992)
(characterizing plurality opinions in Price Waterhouse v. Hopkins,
490 U.S. 228 (1989), as requiring proof that illegitimate factor "had a
'motivating' or 'substantial' role" in employment decision). While the
phrase "motivating factor" is perhaps a more precise and more typical
statement of the standard for liability in ADEA cases, the trial court's use
of "substantial factor" adequately stated the law in this case.