shall

As used in statutes, contracts, or the like, this word is generally imperative or mandatory. In common or ordinary parlance, and in its ordinary signification, the term "shall" is a word of command, and one which has always or which must be given a compulsory meaning; as denoting obligation. The word in ordinary usage means "must" and is inconsistent with a concept of discretion. People v. Municipal Court for Los Angeles Judicial Dist., 149 C.A.3d 951, 197 Cal.Rptr. 204, 206.

It has the invariable significance of excluding the idea of discretion, and has the significance of operating to impose a duty which may be enforced, particularly if public policy is in favor of this meaning, or when addressed to public officials, or where a public interest is involved, or where the public or persons have rights which ought to be exercised or enforced, unless a contrary intent appears. People v. O'Rourke, 124 Cal.App. 752, 13 P.2d 989, 992.

But it may be construed as merely permissive or directory (as equivalent to "may"), to carry out the legislative intention and in cases where no right or benefit to any one depends on its being taken in the imperative sense, and where no public or private right is impaired by its interpretation in the other sense. Wisdom v. Board of Sup'rs of Polk County, 236 Iowa 669, 19 N.W.2d 602, 607, 608