[1][2][3] In civil law, the vacatio legis is "a period of time between announcement of the legal act and its moment of entry into force".
That kind of regulation as legal act must have a proper announcement, which means that it must be published in official state journal".
For very remote countries even a longer time has been conceded, in order to let the knowledge of the law become sufficiently disseminated to make its enforcement possible.
In more recent times the Holy See has in important laws frequently specified the period of the vacatio legis, as for instance in the case of the decree Ne Tenure which was published about eight months before it was to be enforced.
It is not necessary, hence, that the bishop announce to his clergy the laws and regulations passed by the supreme authority of the Church, nor can it be said that this is his duty, though for uniformity of action on part of the clergy of a diocese it is advantageous that the bishop announce to his priests the important new laws with direction to make them known on one and the same day to the people throughout the diocese.