Okla. Stat. tit. 18, § 1128

DEFECTIVE ORGANIZATION OF CORPORATION AS DEFENSE A. No corporation of this state and no person sued by any such organization shall be permitted to assert the want of legal organization as a defense to any claim. B. This section shall not be construed to prevent judicial inquiry into the regularity or validity of the organization of a corporation, or its lawful possession of any corporate power it may assert in any other suit or proceeding where its corporate existence or the power to exercise the corporate rights it asserts is challenged, and evidence tending to sustain the challenge shall be admissible in any such suit or proceeding.