A. It is lawful for a grower, his agent, or a federally licensed hemp producer to grow, a handler or his agent to handle, or a processor or his agent to process industrial hemp in the Commonwealth for any lawful purpose. No federally licensed hemp producer or grower or his agent shall be prosecuted under Chapter 11 (§ 4.1-1100 et seq.) of Title 4.1 or § 18.2-247, 18.2-248, 18.2-248.01, 18.2-248.1, or 18.2-250 for the possession or growing of industrial hemp or any Cannabis sativa with a tetrahydrocannabinol concentration that does not exceed the total tetrahydrocannabinol concentration percentage established in federal regulations applicable to negligent violations located at 7 C.F.R. § 990.6(b)(3). No handler or his agent or processor or his agent shall be prosecuted under Chapter 11 (§ 4.1-1100 et seq.) of Title 4.1 or § 18.2-247, 18.2-248, 18.2-248.01, 18.2-248.1, or 18.2-250 or issued a summons or judgment for the possession, handling, or processing of industrial hemp. In any complaint, information, or indictment, and in any action or proceeding brought for the enforcement of any provision of Article 1 (§ 18.2-247 et seq.) of Chapter 7 of Title 18.2 or the Drug Control Act (§ 54.1-3400 et seq.), it shall not be necessary to negate any exception, excuse, proviso, or exemption contained in this article or the Drug Control Act, and the burden of proof of any such exception, excuse, proviso, or exemption shall be on the defendant.