Peremptory; obligatory; required; that which must be subscribed to or obeyed.
Mandatory statutes are those that require, as opposed to permit, a particular course of action. Their language is characterized by such directive terms as "shall" as opposed to "may." A mandatory provision is one that must be observed, whereas a directory provision is optional.
An example of a mandatory provision is a law that provides that an election judge must endorse his or her initials on a ballot.