Use caution in firing employee after On-the-Job injury

Q. An employee in our plant was directed by a replacement line supervisor to use a machine that he wasn't trained to operate. The employee stuck his hand into the machine to clear a jam and was injured. The plant supervisor fired the employee while he was still in the hospital for operating machinery he hadn't been trained on. Does the employee have a right to sue us if he was actually ordered by the line supervisor to do this job? —K.C.