If it is a public law, as you say, this act applies, whether or not I issue a directive. However, as you well know since you are a lawyer, collective agreements can create confusion, because unions may have a different point of view. In some cases, for instance when the seniority principle applies to pilots or flight attendants, employment rights come into play. Often—
Evidence of meeting #20 for Official Languages in the 42nd Parliament, 1st Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was languages.
A video is available from Parliament.