By having a tough anti-discrimination policy and a clear complaint procedure, you establish what lawyers call an "affirmative defense," meaning you have a weapon to defend yourself in court. But you must put forth those affirmative defenses very early in a lawsuit. If you don't tell your lawyer all the specifics about your policies and investigation procedures, he or she may miss them.
So, that means one of the first things you need to do when slapped with a lawsuit or an EEOC or state discrimination complaint is explain your policies to your lawyers and give them copies of it, plus any investigative records you hold. As the following case shows, perfectly written policies and airtight investigations won't help in court if you don't show those cards early.
Recent case: Corrections officer Angela Jones filed an internal complaint, claiming her supervisor made sexual advances and took bets on who would get her into bed first. The employer investigated the complaint, hearing 14 witnesses and issuing a 31-page report that concluded Jones hadn't been harassed. Still, she filed a sexual harassment lawsuit anyway.
Unfortunately, the court let the case go to trial because the employer didn't bother raising its affirmative defense (that it had an anti-bias policy and did do a thorough investigation) until late in the litigation. The court said that's too late unless the employer could come up with a good reason it didn't mention the defense earlier. It couldn't. (Jones v. DC Department of Corrections, 04-7181, DC Circuit Ct. of Appeals, 2005)