(1) The rules of an organisation may provide for the filling of a casual vacancy in an office by an ordinary election or, subject to this section, in any other manner provided in the rules.
(2) Rules made under subsection (1) must not permit a casual vacancy, or a further casual vacancy, occurring within the term of an office to be filled, otherwise than by an ordinary election, for so much of the unexpired part of the term as exceeds:
(a) 12 months; or
(b) three - quarters of the term of the office;
whichever is the greater.
(3) Where, under rules made under subsection (1), a vacancy in an office in an organisation is filled otherwise than by an ordinary election, the person filling the vacancy must be taken, for the purposes of the relevant provisions, to have been elected to the office under the relevant provisions.
(4) A reference in this section to the rules of an organisation includes a reference to the rules of a branch of the organisation.
(5) In this section:
"ordinary election" means an election held under rules that comply with section 143.
"relevant provisions" , in relation to an organisation, means:
(a) the provisions of this Act (other than this section); and
(b) the rules of the organisation (other than rules made under subsection (1)) providing for the filling of a casual vacancy in an office otherwise than by an ordinary election.
"term" , in relation to an office, means the total period for which the last person elected to the office by an ordinary election (other than an ordinary election to fill a casual vacancy in the office) was entitled by virtue of that election (having regard to any rule made under subsection 145(2)) to hold the office without being re - elected.