Iowa Code § 730.2: Blacklisting employees — treble damages.

If any railway company or other company, partnership, or corporation shall authorize or allow any of its or their agents to blacklist any discharged employee, or attempt by word or writing or any other means whatever to prevent such discharged employee, or any employee who may have voluntarily left said company’s service, from obtaining employment with any other person or company, except as provided for in section 730.1, such company or partnership shall be liable in treble damages to such employee so prevented from obtaining employment.