Okla. Stat. tit. 40, § 40-78: Evidence of age of child - Certificate of physical fitness

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.