Iowa Code § 730.1: Statements regarding discharge.

If any person, agent, company, or corporation, after having discharged any employee from service, shall prevent or attempt to prevent, by word or writing of any kind, such discharged employee from obtaining employment with any other person, company, or corporation, except by furnishing in writing on request a truthful statement as to the cause of the person’s discharge, such person, agent, company, or corporation shall be guilty of a serious misdemeanor and shall be liable for all damages sustained by any such person.