1. If any question as to the validity of any law, having regard to the provisions of the Constitution, shall arise in any action or matter the party having carriage of the proceedings shall forthwith serve notice upon the Attorney General, if he is not already a party.

2. If any question as to the interpretation of the Constitution, other than a question referred to in rule 1, shall arise in any action or matter, the party having carriage of the proceedings shall, if the Court so directs, serve notice upon the Attorney General.

3. Such notice shall state concisely the nature of the proceedings in which the question or dispute arises and the contention or respective contentions of the party or parties to the proceedings.

4. The Attorney General shall thereupon be entitled to appear in the act ion or matter and become a party thereto as regards the question which arises.