Okla. Stat. tit. 5, § 7

It shall be lawful for an attorney to contract for a percentage or portion of the proceeds of a client's cause of action or claim not to exceed fifty percent (50%) of the net amount of such judgment as may be recovered, or such compromise as may be made, whether the same arises ex contractu or ex delicto, and no compromise or settlement entered into by a client without such attorney's consent shall affect or abrogate the lien provided for in this chapter. Provided that all such contracts in personal injury or wrongful death cases including, but not restricted to, cases in which jurisdiction is in the Industrial Commission, shall be void and unenforceable (1) if secured as a result of the intervention of any laymen, association, or corporation for compensation, or promise of compensation, or anticipation of gift, compensation or hope of reward, or (2) where any laymen, association or corporation has a direct or indirect interest in, or growing out of, any judgment arising out of such claim recovery or compensation from, or settlement of any such claim.