Okla. Stat. tit. 17, § 12

The Commission is authorized to have depositions taken upon the application of either party to any cause pending before it, or upon its own motion; and it is further authorized to designate a person to take depositions under such rules and regulations as may be prescribed by the Commission: Provided, that any party to a proceeding before the Commission may take depositions in the same manner as in actions pending in the courts of the state.