When the state asserts a violation of this part, the state need not negative any exemption or exception from the requirements of this part in any pleading or in any trial, hearing, or other proceeding. The burden of proof with respect to any exemption or exception rests upon the person claiming its benefit.
Source:
Section 111850, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=HSC§ionNum=111850..