Okla. Stat. tit. 40 § 78
The Commissioner or his designee, truant officer, or other person charged with the administration of this article, may make demand on an employer in whose factory or establishment a child apparently under the age of sixteen (16) years is employed or permitted or suffered to work, and whose employment certificate is not then filed as required by this section, that such employer shall either furnish him, within ten (10) days, evidence satisfactory to him that such child is in fact over sixteen (16) years of age, or shall cease to employ or permit or suffer such child to work in such factory or establishment. Such officer may require from such employer the same evidence of age of such child as is required on the issuance of an employment certificate; and the employer furnishing such evidence shall not be required to furnish any further evidence of the age of the child. In case such employer shall fail to produce and deliver to such officer, within ten (10) days after such demand, such evidence of age herein required by him, and shall thereafter continue to employ such child to work in such factory or establishment, proof of the giving of such notice and of such failure to produce and file such evidence shall be prima facie evidence in any prosecution brought for violation of this provision of this article that such child is under sixteen (16) years of age and is unlawfully employed: Provided, that the Commissioner or his designee shall have the power to demand a certificate of physical fitness from some licensed physician in good standing in this state in case of children who may appear to him physically unable to perform the labor at which they may be engaged, and shall have power to prohibit the employment of any minor that cannot obtain such a certificate.
Okla. Stat. tit. 40, § 78