Former WA senator Brian Greig says a leaked draft of a proposed marriage equality plebiscite question leaves open the option of a separate law for same-sex marriages.
The Sunday Telegraph reported that the draft question under consideration by the government is, "Do you approve of a law to permit people of the same sex to marry?"
The former Democrat senator told BuzzFeed News there are problems with the phrasing.
"It suggests the government is not looking to include people in the existing act, it is looking to add an act," he said.
"We must avoid having a segregated system of parallel marriages, one for straight people and one for non-straight people."
Dean of the UNSW Faculty of Law George Williams told BuzzFeed News it would be entirely possible to have a separate law allowing same-sex marriages.
"There would need to be amendments to the existing Marriage Act, because otherwise it would give rise to inconsistency," he said.
"If you cleared out those inconsistencies, you could still have separate legislation providing for same-sex marriage."
A spokesperson for attorney-general George Brandis did not rule out the possibility.
"The mechanics of the plebiscite are subject to the usual cabinet processes and no decision has been made," the spokesperson said.
However, Williams said he "can't see any point" to such a proposal.
"Of course, it might send an unfortunate signal about whether same-sex marriage is on par with other forms of marriage," he said.
Greig and other advocates have also expressed concern that the draft question does not include all people with the wording "same sex".
GetUp! campaigner Sally Rugg said the draft question "excludes intersex people and people without a binary gender identity through the prescriptive wording 'same-sex marriage'."
Williams echoed these concerns, saying the best way to legislate for marriage equality would be not include the words "same sex" at all.
"The best way would be to amend the definition of marriage, in the Marriage Act, to make it clear it applies not just to heterosexual couples but marriage generally between two people."