Legal provisions for optional referendums at national level

Constitution ss 128 and 123 (mandatory referendums)

See generally Graeme Orr ‘The Conduct of Referenda and Plebiscites in Australia: a Legal Perspective’ (2000) 11 Public Law Review 117

The only ‘optional’ referendums have been ad hoc, consultative referendums (what is locally known as a non-binding / plebiscite) heldin 1917 (conscription) and 1977 (national song).  There is NO standing legal provision for such ‘optional referendums’.  The national parliament can just pass an ad hoc law to hold one (e.g. Military Service Referendum Act 1916).