The government could hold a marriage equality plebiscite without passing legislation through the parliament, but would have to radically alter the current proposal for a compulsory vote.
Malcolm Turnbull introduced a marriage equality plebiscite bill into the parliament on Wednesday, proposing a compulsory public vote for February 2017, but Labor is set to block the legislation in the senate.
However, the government could still keep its election promise by contracting the Australian Electoral Commission to hold a "fee-for-service" election, polling the Australian people on marriage equality.
During a 2015 senate inquiry into a same-sex marriage plebiscite, chief legal officer of the AEC Paul Pirani advised that a plebiscite could be held without enabling legislation.
The AEC and state electoral commissions regularly conducts such polls for public and private sector organisations.
However, holding a plebiscite without legislation would mean the government letting go of many of the central elements of its current plebiscite policy.
Compulsory voting, an official dispute resolution process, and public funding would all be at risk.
Dean of the UNSW Faculty of Law, George Williams, told BuzzFeed News a fee-for-service plebiscite "may be attractive to the government if they can’t get this bill through the senate".
Williams warned a “pared back plebiscite” would be “unwise and dangerous”.
“It doesn’t set down proper rules for things like disputing the result to determine if a ballot has been cast properly. It’s also not possible to have compulsory voting,” he said.
The government’s proposed $15 million in public funding would also be at risk of a legal challenge.
“It would be difficult [to introduce] because there wouldn’t be a legislative basis for it,” Williams said. “They could try, but it would likely be subject to court challenge.”
The government could still determine aspects such as the question and timing of the vote, which would be set out in a memorandum of understanding between the AEC and the relevant government department.