Cal. Gov't Code § 82048.4

(a) “Slate mailer organization” means, except as provided in subdivision (b), any person who, directly or indirectly, does all of the following:
1. (1) Is involved in the production of one or more slate mailers and exercises control over the selection of the candidates and measures to be supported or opposed in the slate mailers.
2. (2) Receives or is promised payments totaling five hundred dollars ($500) or more in a calendar year for the production of one or more slate mailers.
(b) Notwithstanding subdivision (a), a slate mailer organization shall not include any of the following:
1. (1) A candidate or officeholder or a candidate’s or officeholder’s controlled committee.
2. (2) An official committee of any political party.
3. (3) A legislative caucus committee.
4. (4) A committee primarily formed to support or oppose a candidate, officeholder, or ballot measure.
(c) The production and distribution of slate mailers by a slate mailer organization shall not be considered making contributions or expenditures for purposes of subdivision (b) or (c) of Section 82013. If a slate mailer organization makes contributions or expenditures other than by producing or distributing slate mailers, and it reports those contributions and expenditures pursuant to Sections 84218 and 84219, no additional campaign reports shall be required of the slate mailer organization pursuant to Section 84200 or 84200.5.