An employer has the right to set the terms and conditions of employment, including setting a dress code. That dress code can address jewlery, body art, piercings, etc., as well as clothing.Like or not, women and men do traditionally dress differently, and the expectations for what consitutes acceptable dress, especially in a professional or office environment, vary--for example, a woman could wear a skirt or skirt suit to work, while a man could not. While an employer may not discriminate against a worker on the basis of gender or sex, an employer may still set certain reasonable gender-based rules. Given the different societal expectations for how men and women dress, and the employer's basic right to set dress codes, it is highly unlikely any court would conclude that an employer may not ban male earings; thus, it is highly likely this is perfectly legal.