P.R. Laws tit. 24, § 2514
(a)
(1) It shall not be necessary for the Commonwealth to negative any exemption or exception set forth in this chapter in any complaint, arraignment, or other pleading or in any trial, hearing or other judicial proceeding, in conformity with this chapter and the burden of the proof of such exemption or exception shall be upon the person claiming its benefits.
(2) In the case of a person charged under § 2404(a) of this title with the possession of a controlled substance, any label identifying same in accordance with § 503(b)(2) of the Federal Food, Drug and Cosmetic Act shall be admissible in evidence and shall be prima facie evidence that such substance was obtained pursuant to a valid prescription from a practitioner while acting in the course of his professional practice.
(b) In the absence of proof that a person is the duly authorized holder of a registration or of an official order form, issued under this chapter, it shall be presumed that he is not the lawful holder of such registration or form, and to such person shall correspond the burden of proof to refute such presumption.
(c) The burden of proof to establish that a conveyance, including aircraft, vehicle, mount or vessel used in connection with substances in Schedule I, was lawfully used under the provisions of this chapter shall correspond to the persons engaged in such use.
History —June 23, 1971, No. 4, p. 526, § 514; May 31, 1972, No. 64, p. 139, § 2.