California Code, Government Code - GOV § 66655

If, prior to September 1, 1969, any city or county has adopted an ordinance or issued a permit authorizing a particular use or uses within the areas defined in subdivisions (b), (c) and (d) of Section 66610, no person who has obtained a vested right thereunder shall be required to secure a permit from the commission, providing, that no substantial changes may be made in any such use or uses, except in accordance with this title. Any such person shall be deemed to have such vested rights if, prior to September 1, 1969, he has in good faith and in reliance upon the ordinance or permit commenced and performed substantial work on the use or uses authorized and incurred substantial liabilities for work and materials necessary therefor. Expenses incurred in obtaining the enactment of an ordinance or the issuance of a permit shall not be deemed liabilities for work or material.