The arguments made by the Obama Departments of Educations and Justice, that it was already existing law that sex discrimination under Titles VII and IX covered gender orientation, relied almost entirely on the Supreme Court’s decision in Price Waterhouse v. Hopkins.
But the Obama administration, relying on Supreme Court decisions and other precedents going back several years, has interpreted the statute to include protections for gender identity, and issued guidance to schools to provide accommodations for trans students.
But was there such precedent, or was it merely a claim, relying on a decision that, if viewed through squinted eyes, could kinda, sorta be twisted into precedent?
The decision was, in fact, a relatively straightforward sex discrimination case that happened to involve a trans man, whom the Court discussed as a woman, and concluded that she (not he, not xi, not hir, but she) was discriminated against as a woman because she wasn’t appropriately feminine. The holding was that discrimination against women based on gender stereotypes violated Title VII.

