With respect to gender stereotypes:
[A]n employer who acts on the basis of a belief that a woman cannot be aggressive, or that she must not be, has acted on the basis of gender. ... [W]e are beyond the day when an employer could evaluate employees by assuming or insisting that they matched [sic] the stereotype associated with their group.... An employer who objects to aggressiveness in women but whose positions require this trait places women in an intolerable and impermissible catch 22: out of a job if they behave aggressively and out of a job if they do not. Title VII lifts women out of this bind.
Price Waterhouse v. Hopkins, 490 U.S. 228, 250-51 (1989) (Brennan, J., plurality opinion).