Answer:
Dress codes highlight an odd fact about sex discrimination cases: While laws prohibiting sex discrimination require employers to treat men and women equally, our society is still comfortable with the belief that there are fundamental cultural differences between the genders. Of course, no one disputes the basic biological fact that males and females generally have different body parts and different roles in the reproductive process. But culturally, many people still believe that men and women think and act differently (Mars and Venus, anyone?), express themselves differently, should play different roles in the family and close relationships, and yes, should dress differently.
Courts have grappled with how to handle this disconnect. On the one hand, employees in cases involving sex-based stereotypes have generally done well. In these cases, the employee is disciplined or fired for not conforming to the employer's notion of how men and women should act. In the Supreme Court case that paved the way for these employees, a woman successfully sued after she was denied partnership at the accounting firm Price Waterhouse. She was told she was too aggressive, needed to speak, act, and dress more femininely, and needed "a course in charm school." She succeeded in showing that these comments demonstrated that her employer penalized her for failing to live up to its idea of how women should behave, which is sex discrimination.
Dress code cases have taken a different turn, however. Generally, federal courts have upheld dress codes that require men and women to dress or groom themselves differently, and in a manner that conforms with gender stereotypes. Rules like those you describe have often been allowed: short hair for men but not women; suits for men and dresses or skirts for women; makeup prohibited for men but allowed or required for women, and so on. In fact, some courts have even allowed gender-based dress codes that create a more sexual image for women. Harrah's casino, for example, was allowed to require women to tease, curl or style their hair; to wear stockings; and to wear specific types of makeup, including lip color. These requirements are clearly intended to make female employees look more sexualized and more attractive in an entirely gender-based way, yet the court upheld them.
A court might step in if a dress code places a heavier burden on one gender. For example, if women were required to wear an elaborate costume and men had no dress code, that might be enough to cross the line. This is one possible line of attack in your case: Because women have to wear a particular brand of clothing and men do not, you might have a plausible claim if you are forced to spend more on your work wear. Even so, it wouldn't be much to hang a lawsuit on.
As gender identity and transgender legal issues get more attention, this disconnect will undoubtedly grow. These cases push back against cultural notions about what gender is and what role society should play in policing how it is expressed. In the meantime, however, it might be time for you to go shopping for a skirt and some makeup -- or a new job. Or a lawyer.
