§47-158.2.

§47-158.2.
   
   The operation of such vehicles, motorized machinery and equipment by
   the departments described in Section 158.1 of this title 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 Act
   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 Oklahoma State
   Penitentiary.