Federal and state laws are clear about sex discrimination in the workplace. It was banned in Title VII of the Civil Rights Act of 1964, which came shortly after the Equal Pay Act of 1963. The sex discrimination laws have also been amended several times to include wider powers like pregnancy discrimination. It is illegal for any employer to discriminate on the basis of sex, gender, or gender identity, including transgender status, or because of sexual orientation.
This applies in any of the following employment situations: Hiring, and firing employees, Awarding pay, Making job assignments, Deciding on promotions and demotions, Laying off employees, Training employees, Fringe benefits, Other terms or conditions of employment.
The state and federal laws protect both women and men equally, as well as transgender status. Note also that your employer does not have to be of a different sex to discriminate. A woman discriminating against another woman on the basis of her gender is still breaking the law.