Okla. Stat. tit. 66 § 57
The provisions of this article with reference to eminent domain shall apply to all corporations having the right to eminent domain, and shall apply to the State of Oklahoma and its various educational, reformatory, penal and eleemosynary institutions, including departments of state having the power to purchase real property for public purposes, and such institutions and departments shall have the right under this article to acquire fee simple title to the property taken. When the State of Oklahoma through the managing board or commission of the institution or department of state concerned is unable to purchase any real property needed for any such institution or department, condemnation proceedings to take the same and to pay damages therefor may be instituted in the name of the State of Oklahoma by the managing board or commission of the institution or department of state involved; and all such institutions and corporations shall have the right, under the provisions of this article, to acquire right-of-way over, under, along or across the property or right-of-way of any other such corporation, not inconsistent with the purposes for which such property was taken or acquired. In all cases of condemnation of property for either public or private use, the determination of the character of the use shall be a judicial question; and the procedure shall be as provided herein: Provided, that in case any corporation or municipality authorized to exercise the right of eminent domain shall have taken and occupied, for purposes for which it might have resorted to condemnation proceedings, as provided in this article, any land, without having purchased or condemned the same, the damage thereby inflicted upon the owner of such land shall be determined in the manner provided in this article for condemnation proceedings.
Okla. Stat. tit. 66, § 57