3. Mechanics, persons furnishing materials, artisans, and laborers of every class, shall have a lien upon the property upon which they have bestowed labor or furnished material for the value of such labor done and material furnished; and the Legislature shall provide, by law, for the speedy and efficient enforcement of such liens. (Adopted June 8, 1976.)
The persons entitled to claim liens are listed in the California Civil Code, section 3110.
A mechanics lien is filed in the County Recorder's Office on the property where the work was performed and services delivered. It can be enforced through a court action to foreclose the mechanics lien. This is filed in the applicable state court with a cause of action for the breach of contract. Once payment or a settlement has been obtained, the action should be dismissed and the lien should be released. If the consumer has paid and the lien is not removed, they have remedies under state law.
Links:
California State Contractors Board
San Francisco Planning Dept. - This site provides zoning and permit information.