And unemployment might agree with you. Present your side of the story. What was known by all employees - official policy and what was normally practised such that this employee should have known he / she was in the wrong. It might be as simple as, no one ever ever took the truck before from you or anyone else in this position. The person may have been too new. Was there something to cause this person to act outside what was normal and had come to be relied upon by all?