Okla. Stat. tit. 44, § 72

It shall be the duty of the Governor, and he or she is authorized and required, in case of war, invasion, insurrection, or breach of the peace or imminent danger thereof or any forcible obstructing of the execution of the laws or reasonable apprehension thereof, or an imminent or existing epidemic or pandemic, and at all other times he or she may deem necessary, to order on state active duty the National Guard or any part thereof. No member thereof who shall be ordered out for such state active duty shall be liable for civil prosecution for any act done by him or her in the discharge of his or her military duty on such occasions. Laws 1951, p. 117, art. 4, § 2, eff. May 16, 1951.