In its brief, the EEOC lays out its argument that "Sexual orientation is cognizable as sex discrimination under Title VII." The headings from its brief:
A. Sexual orientation discrimination necessarily involves sex stereotyping, in violation of Title VII
B. Sexual orientation discrimination constitutes associational discrimination that violates Title VII
C. Sexual orientation discrimination is, by definition, discrimination “because of . . . sex,” in violation of Title VII.
D. The contrary cases on which the district court relied are not persuasive authorityI think the EEOC is fighting an uphill battle here, but I guess we'll see. Homosexual employees have had some success arguing the "gender stereotyping" theory. For an example from the Third Circuit, see Prowel v. Wise Business Forms, Inc. (prior Lawffice Space coverage here).