It’s a simple fact: You can’t tell which of your employees might sue you one day or for what reason. Your only real protection is fairness.
If you treat all employees equally and provide them with the same opportunities, training and discipline, chances are any lawsuit will eventually be dismissed.
Recent case: Mark East was a firefighter. His fire company had a rule against careless slander and spreading unsubstantiated rumors. Still, East started spreading the word that several other firefighters were being fired for misappropriating funds and drunk driving. It was not true. East was ultimately fired for breaking the no-rumors rule.
He sued for age discrimination, but lost his case. He could not point to any direct age discrimination, nor could he show that someone younger than he had broken the same rule but was disciplined differently. (East v. Clayton County, No. 10-15749, 11th Cir., 2011)