Okla. Stat. tit. 73 § 158.1
All bonds issued hereunder shall have on the backs thereof the certificate required by Section 29 of Article X of the Constitution of Oklahoma. Such bonds and any bonds or other obligations issued by the Oklahoma Capitol Improvement Authority shall be submitted to the Attorney General of Oklahoma for examination; and such bonds, when having been examined and certified as legal obligations by the Attorney General in accordance with such requirements as he or she may make, shall be incontestable in any court in the State of Oklahoma unless suit thereon shall be brought in a court having jurisdiction thereof within thirty (30) days from the date of such approval. Bonds so approved by the Attorney General shall be prima facie valid and binding obligations according to their terms, and the only defense which may be offered thereto in any suit instituted after such thirty-day period shall have expired shall be forgery, fraud or violation of the Constitution.
Okla. Stat. tit. 73, § 158.1