The State need not negate an exemption, proviso, or exception set forth in this title in: a complaint, information, indictment, or other pleading; or a trial, hearing, or other proceeding under this title. The burden of proof to establish an exemption, proviso, or exception is on the person claiming its benefit. In the absence of proof that a person is a registrant or holder of an order form issued under § 5–303(d) of this title, the person is presumed not to be a registrant or holder of a form. The person has the burden of proof to rebut the presumption.