Sex or gender discrimination is the different treatment of individuals in their employment because of their biological sex, gender identity, or gender expression. If you have been rejected for employment, fired, or otherwise experienced different treatment in the workplace because of your sex or gender, you may have suffered from this kind of discrimination. Although sex-based discrimination is illegal under numerous federal and state laws, there are circumstances in which it may be permissible under a legal exception or where discriminatory conduct may not meet the legal requirements to prevail in court.