18.—(1) Except where rule 12 above applies, the Tribunal shall determine whether to uphold any objection of the relevant Minister under rule 13 above, and any application under rule 17 above, in accordance with this rule.
(2) Subject to paragraph (3) below, proceedings under this rule shall take place in the absence of the parties.
(3) The relevant Minister may attend any proceedings under this rule, whether or not he is a party to the appeal in question.
(4) An objection under rule 13 above must be considered under this rule as a preliminary issue, and an application under rule 17 above may be considered as a preliminary issue or at the hearing of the substantive appeal.
(5) Where, in the case of an objection under rule 13 above, the Tribunal is minded to overrule the relevant Minister’s objection, or to require him to provide a version of his notice in a form other than that which he provided it under rule 13(3)(b) above, the Tribunal must invite the relevant Minister to make oral representations.
(6) Where the Tribunal under paragraph (5) above overrules an objection by the relevant Minister under rule 13 above, or requires him to provide a version of his notice in a form other than that in which he provided it under rule 13(3)(b) above, the Tribunal shall not disclose, and the relevant Minister shall not be required to disclose, any material which was the subject of the unsuccessful objection if the relevant Minister chooses not to rely upon it in opposing the appeal.
(7) Where, in the case of an objection under rule 13 above, the Tribunal upholds the relevant Minister’s objection and either–
(a)approves the version of his notice provided under rule 13(3)(b), or
(b)requires him to provide a version of his notice in a form other than that in which he provided it under rule 13(3)(b),
rule 8(3) above applies to that version of the notice.