Actually, if someone is an "at-will" employee in the U.S. (http://en.wikipedia.org/wiki/At-will_employment), you don't need any reason at all to fire him. Certainly gross insubordination (such as refusing to do a job when asked) is something that people are fired for all the time. Paper trails are useful when the employee is a member of a protected class and could allege in a law suit that they were fired because they were a minority, pregnant, over 40, etc. But that doesn't seem to apply to the original poster's situation.