On an external review, the information commissioner must do all things necessary to ensure that any document that is given to the commissioner and is the subject of the decision being reviewed—
(a) is not disclosed to a person other than—
(i) a member of the staff of the OIC in the course of performing duties as a member of the staff; or
(ii) a person who created the document or who gave the document or information in the document to the agency or Minister; or
(iii) if a person mentioned in subparagraph (ii) is a participant in the review—the participant's representative; and
(b) at the end of the review, is returned to the person who gave it.
(2) Despite subsection (1)(b), if an agency or Minister gives the commissioner a copy of a document for an external review, the commissioner may destroy the copy at the end of the review.