Paragraph 4.3 References under section 11

If the First Minister and the deputy First Minister (acting jointly) or any Law Officer (other than the Attorney General for Northern Ireland) wishes to participate in the proceedings he shall within 14 days of service of the reference on him enter an appearance and serve notice of having done so on the Attorney General for Northern Ireland; and any person entering an appearance in accordance with this rule shall thereupon become a respondent to the proceedings.