Can. 30 A general decree, as in can. 29, cannot be made by one who has only executive power, unless in particular cases this has been expressly authorized by the competent legislator in accordance with the law, and provided the conditions prescribed in the act of authorization are observed.
Can. 31 §1 Within the limits of their competence, those who have executive power can issue general executory decrees, that is, decrees which define more precisely the manner of applying a law, or which urge the observance of laws.
§2 These decrees cease to have force by explicit or implicit revocation by the competent authority, and by the cessation of the law for whose execution they were issued. They do not cease on the expiry of the authority of the person who issued them, unless the contrary is expressly provided.
Can. 34 §1 Instructions, namely, which set out the provisions of a law and develop the manner in which it is to be put into effect, are given for the benefit of those whose duty it is to execute the law, and they bind them in executing the law. Those who have executive power may, within the limits of their competence, lawfully publish such instructions.
§3 Instructions cease to have force not only by explicit or implicit revocation by the
competent authority who published them or by that authority’s superior, but also by the
cessation of the law which they were designed to set out and execute.