California Code, Streets and Highways Code - SHC § 35530

(a) When an assessment made, issued, or filed in the office of the clerk, or any bonds issued to represent the amounts of any such assessment, have been set aside by a court of competent jurisdiction, or when the court has refused to enforce an assessment or has decreed any such bonds not to constitute or represent valid and subsisting liens against the lots or parcels of land upon which the assessments represented by them have been levied.

(b) If for any reason the assessments or bonds, or both, are not effective and the curative and waiver provisions of this chapter or any curative act passed by the Legislature in relation to them fail to make them valid and enforceable.

(c) Upon the initiative of the legislative body if the legislative body is of the opinion that all or any part of the assessments or bonds are not enforceable.