Okla. Stat. tit. 40, § 172

No firm, corporation or individual shall blacklist or require a letter of relinquishment, or publish, or cause to be published, or blacklisted, any employee, mechanic or laborer, discharged from or voluntarily leaving the service of such company, corporation or individual, with intent and for the purpose of preventing such employee, mechanic or laborer, from engaging in or securing similar or other employment from any other corporation, company or individual.