You will never know which employee will sue or for what reason. That’s a good reason to carefully track all discipline and make the records easy to access. If sued, you’ll need to show that all employees who broke the same rule were punished the same way, regardless of their race, gender or other protected characteristic.
Recent case: Crystal was fired under her company’s attendance policy for allegedly failing to show up for her scheduled shift. She was pregnant at the time and sued, alleging she had really been fired because she was about to go on.
But the company was ready with figures that showed it had also fired 31 employees who weren’t pregnant for breaking the same no-show policy. That was enough to get the case tossed out. (Delp v. Rolling Fields, No. 10-285, WD PA, 2012)