In Morris v. County of Marin (1977) 18 Cal.3d 901, the Legislature mandated in Labor Code section 3800 that counties require applicants for a building permit to have workers' compensation insurance. The statute provided that "every county ... which requires a building permit ... shall require that each applicant for such permit" have on file a certificate of workers' compensation insurance. The court found that, in using this language, the Legislature "intended the filing of a 'certificate of insurance' to constitute a condition precedent to the issuance of a building permit" and thus imposed a mandatory duty under section 815.6. (Morris, supra, at p. 907 & fn. 3.) The state Supreme Court explained the difference between mandatory and directory statutory requirements. "The term 'mandatory' refers to an obligatory duty which a governmental entity is required to perform, as opposed to a permissive power which a governmental entity may exercise or not as it chooses. By contrast, the 'directory' or 'mandatory' designation does not refer to whether a particular statutory requirement is 'permissive' or 'obligatory,' but instead simply denotes whether the failure to comply with a particular procedural step will or will not have the effect of invalidating the governmental action to which the procedural requirement relates." ( Id. at p. 908.)