Any person or persons suffering damages from the claimed negligent acts of any of such departments, their officers, servants, employees, or agents, arising from the operation of the vehicles, motorized machinery, or equipment so insured is hereby authorized to maintain an action to collect damages against the insurer. The insurer may not plead as a defense in any action involving insurance purchased by the authority of this act the governmental immunity of either the State of Oklahoma, the State Highway Department, the State Department of Agriculture, or the State Department of Public Welfare, or any other subdivision of state government.
Laws 1961, p. 545, § 3.