In harassment cases that do not involve harassment by a supervisor that resulted in a tangible employment action, an employer has a defense if it can prove two things:
The first prong of the test requires the employer to show that it took reasonable care to prevent and promptly correct any harassment. Simply having a policy is not enough; the policy must be implemented. Not having a formal policy will not necessarily defeat the defense if the employer exercised sufficient care through other means, but not having a policy makes it very difficult for an employer to show that it exercised reasonable care. Therefore, it is best to have a policy in place.