18-12-302 (2):
(2) (a) A person may possess a large-capacity magazine if he or she:
(I) Owns the large-capacity magazine on July 1, 2013; and
(II) Maintains continuous possession of the large-capacity magazine.
(b) If a person who is alleged to have violated subsection (1) of this section asserts that he or she is permitted to legally possess a large-capacity magazine pursuant to paragraph (a) of this subsection (2), the prosecution has the burden of proof to refute the assertion.