Tanada v. Tuvera, 146 SCRA 446 (1986),
Whether or not publication in the official gazette is indispensable.
YES. The very first clause of Section I of Commonwealth Act 638 reads: "There shall be published in the Official Gazette ... ." The word "shall" used therein imposes upon respondent officials an imperative duty. That duty must be enforced if the Constitutional right of the people to be informed on matters of public concern is to be given substance and reality. The law itself makes a list of what should be published in the Official Gazette. Such listing, to our mind, leaves respondents with no discretion whatsoever as to what must be included or excluded from such publication.
The publication of all presidential issuances "of a public nature" or "of general applicability" is mandated by law. It is a requirement of due process. It is a rule of law that before a person may be bound by law, he must first be officially and specifically informed of its contents. Obviously, presidential decrees that provide for fines, forfeitures or penalties for their violation or otherwise impose a burden on the people, such as tax and revenue measures, fall within this category. Other presidential issuances which apply only to particular persons or class of persons such as administrative and executive orders need not be published on the assumption that they have been circularized to all concerned.
The objective is to give the general public adequate notice of the various laws which are to regulate their actions and conduct as citizens. Without such notice and publication, there would be no basis for the application of the maxim "ignorantia legis non excusat." It would be the height of injustice to punish or otherwise burden a citizen for the transgression of a law of which he had no notice whatsoever, not even a constructive one.