Okla. Stat. tit. 5, § 5-9: Adverse party - Amount of liability on settlement or

compromise.

Should the amount of the attorney's fees be agreed upon in the

contract of employment, then such attorney's lien and cause of

action against such adverse party shall be for the amount or portion

of the property so agreed upon. If the fee be not fixed by contract

the lien and cause of action, as aforesaid, shall be for a

reasonable amount for not only the services actually rendered by

such attorney, but for a sum, which it might be reasonably supposed,

would have been earned by him, had he been permitted to complete his

contract, and been successful in the action, and such attorney in

order to recover need not establish that his client, if the case has

gone to trial, would have been successful in the action, but the

fact of settlement shall be sufficient without other proof to

establish that the party making the settlement was liable in the

action. Should the contract be for a contingent fee and specify the

amount for which action is to be filed, then the lien and cause of

action, as aforesaid shall be for the amount contracted for if fixed

at a definite sum of money or for the percentage of the amount or

property sued for as mentioned in said contract where the fee is

fixed on a percentage basis, not exceeding thirty-three and one-

third percent (33 1/3%) of the amount sued on where the settlement

is before a verdict or judgment and if made after verdict or

judgment then the full contract price.