Employers have a tough call to make if an employee lands a short jail sentence. Discharging the worker may be the best option. But leniency may be more appropriate in other situations.
If you can explain why you treated convicted employees differently, you should be legally OK.
Recent case: Ernest Moon worked for Alcoa as a security guard. Moon pleaded no contest to attempted sexual activity with a minor and served 24 days in jail. He also had a prior conviction for property theft while working security for another company.
Alcoa fired Moon and he sued, alleging that other Alcoa employees who had served short jail sentences weren’t terminated. But it turned out that those employees weren’t security guards and hadn’t stolen anything. Moon’s case was dismissed. (Moon v. Alcoa, No. 1:10-CV-1092, ND OH, 2011)