California Code, Business and Professions Code - BPC § 25246

(a) Any wine labeled with an American Viticultural Area established pursuant to Part 9 (commencing with Section 9.1) of Title 27 of the Code of Federal Regulations, that is located entirely within a county of the 19th class, shall bear the designation “Sonoma County” on the label in a type size not smaller than two millimeters on containers of more than 187 milliliters or smaller than one millimeter on containers of 187 milliliters or less.

(b) The department may suspend or revoke the license of any person who violates this section.

(c) This section shall not apply to any wine labeled with a viticultural area appellation of origin established pursuant to Part 9 (commencing with Section 9.1) of Title 27 of the Code of Federal Regulations when the name of the appellation includes the term “Sonoma County.”

(d) This section shall apply to wines bottled on or after January 1, 2014.