It can be difficult for an employee to prove unlawful retaliation by an employer. However, one factor that is important is the closeness in time (in legal terms called temporal proximity ) between the employee’s complaint of discrimination and the adverse employment action. For example, let’s say an employee complains about sexual harassment and then the employer terminates her only one month later. That closeness in time may be enough to prove unlawful retaliation. It certainly seems to create an inference of unlawful retaliation. On the other hand, if there is a time gap between the protected conduct (complaining about discrimination) and the adverse employment action, then the employee must come up with some other type of evidence of retaliation.