Okla. Stat. tit. 71, § 71-1-503: Evidentiary burden

A. In a civil action or administrative proceeding under this

act, a person claiming an exemption, exception, preemption, or

exclusion has the burden to prove the applicability of the

exemption, exception, preemption, or exclusion.

B. In a criminal proceeding under this act, a person claiming

an exemption, exception, preemption, or exclusion has the burden of

going forward with evidence of the claim.