(1) In this section, an office to which this section applies is:
(a) the office of President of the Commission; or
(b) the office of Deputy President of the Commission.
(2) Subject to section 193, the Minister may appoint one of the commissioners to act in an office to which this section applies:
(a) during a vacancy in that office; or
(b) during any period, or during all periods, when the holder of that office:
(i) is absent from duty or from Australia;
(ii) is suspended under section 188;
(iii) being the Deputy President, is acting in the office of President of the Commission in pursuance of an appointment under this section or section 193; or
(iv) is, for any other reason, unable to perform the functions of that office.
(3) An appointment of a commissioner under subsection (2) may be expressed to have effect only in such circumstances as are specified in the instrument of appointment.
(4) A commissioner appointed to act during a vacancy in an office to which this section applies shall not continue so to act for more than 12 months.
(5) The Minister may:
(a) determine the terms and conditions of appointment, including remuneration and allowances, of a commissioner appointed, under this section, to act in an office to which this section applies; and
(b) at any time, terminate the appointment.
(6) The appointment of a commissioner to act in an office to which this section applies ceases to have effect:
(a) if the commissioner ceases to be a commissioner;
(b) if the commissioner is suspended from office under section 188; or
(c) if the commissioner resigns the appointment by writing signed by the commissioner and delivered to the Minister.
(7) Where a commissioner is acting in an office to which this section applies in accordance with paragraph (2)(b) and that office becomes vacant while the commissioner is so acting, that commissioner may, subject to subsections (3) and (6), continue so to act until the Minister otherwise determines, the vacancy is filled or a period of 12 months from the date on which the vacancy occurred expires, whichever first happens.
(8) While a commissioner is acting in an office to which this section applies, the commissioner has, and may exercise, all the powers, and shall perform all the functions, of that office.
(9) The validity of anything done by a commissioner purporting to act under subsection (2) shall not be called in question on the ground that the occasion for the commissioner's appointment had not arisen, that there is a defect or irregularity in or in connection with the commissioner's appointment, that the commissioner's appointment had ceased to have effect or that the occasion for the commissioner to act had not arisen or had ceased.
(10) The Minister may appoint a person who holds an appointment as acting commissioner under section 191 to act in an office to which this section applies as if the reference in subsection (2) of this section to one of the commissioners included a reference to a person holding an appointment as acting commissioner under section 191 and, if the Minister does so:
(a) subsections (3) to (9), inclusive, of this section apply to and in relation to the person as if the references in those subsections to a commissioner included references to an acting commissioner; and
(b) without limiting the application of those subsections in accordance with paragraph (a) of this subsection, the person so appointed is not entitled to act in that office in pursuance of the appointment under subsection (2) of this section at any time when the person is not acting in an office of commissioner in pursuance of an appointment under section 191.