Okla. Stat. tit. 47, § 47-158.2: Maintenance of actions

The operation of vehicles, motorized machinery and equipment by

the Office of Management and Enterprise Services, the State

Department of Health, the Department of Public Safety, the

Department of Mental Health and Substance Abuse Services, the

Department of Corrections, and all other state departments and

agencies not otherwise specifically authorized by law, is hereby

declared to be a public governmental function. An action for

damages may be brought against such departments, but the

governmental immunity of such departments shall be waived only to

the extent of the amount of insurance purchased. The departments

shall be liable for negligence only while such insurance is in

force, but in no case in an amount exceeding the limits of the

coverage of any such insurance policy. No attempt shall be made in

the trial of any action brought against any such departments to

suggest the existence of any insurance which covers in whole or in

part any judgment or award which may be rendered in favor of the

plaintiff, and if the verdict rendered by the jury exceeds the

limits of the applicable insurance, the court shall reduce the

amount of said judgment or award to a sum equal to the applicable

limits stated in the policy. The insurer may not plead as a defense

in any action involving insurance purchases by the authority of this

section the governmental immunity of either the State of Oklahoma,

the State Department of Health, Department of Public Safety,

Department of Mental Health and Substance Abuse Services, or the

Department of Corrections.