4Subject to rules made by the Lord Chancellor under section 78(2)(c) above, the members who are to constitute a Mental Health Review Tribunal for the purposes of any proceedings or class or group of proceedings under this Act shall be appointed by the chairman of the tribunal or, if for any reason he is unable to act, by another member of the tribunal appointed for the purpose by the chairman; and of the members so appointed—
(a)one or more shall be appointed from the legal members;
(b)one or more shall be appointed from the medical members; and
(c)one or more shall be appointed from the members who are neither legal nor medical members.