Federal and local laws protect employees from sexual harassment. There are two types of sexual harassment. The first type is known as Quid Pro Quo Sexual Harassment: when sex is demanded as a condition of employment. It is illegal for a supervisor to provide preferential treatment to an employee in exchange for sex or to demote or discharge an employee who withholds sexual favors. The second type is Hostile Work Environment Sexual Harassment: when a supervisor or co-worker subjects another to unwelcome sexual attention such as touching, sexually charged jokes, or innuendos. This type of conduct is illegal -- and far too common.
It is also illegal for a co-worker or supervisor to mistreat an employee or treat him or her less favorably than others after that employee discontinues a consensual romantic relationship.
It is illegal for an employer to terminate or mistreat an employee for making sexual harassment complaints. Laws are designed to permit employees to complain about sexual harassment without fear of retaliation. An employer who retaliates against an employee for making a sexual harassment complaint faces the same damages/penalties it would face for sexually harassing against the employee.