Senator Penny Wong has outlined her reasons for opposing a plebiscite on same-sex marriage, in a speech delivered to the Homosexual Histories conference in Adelaide.
Current government policy on same-sex marriage is to take a plebiscite to the next election, whereas Labor has promised to introduce legislation for marriage equality within 100 days if elected.
A plebiscite would poll the entire electorate on marriage equality, but is usually non-binding and does not prompt an automatic change of the law.
Prime minister Malcolm Turnbull has implied a plebiscite on marriage would include binding clauses to ensure the passage of reform if Australia votes 'Yes'. However, the detail remains unknown.
"It's important to acknowledge from the outset, that there has been no principled position articulated for [marriage equality] to be put to a plebiscite instead of being decided on by Parliament," Wong said.
"Australia hasn't had plebiscites on other fundamental issues of justice and human rights – like ending the death penalty, dropping the White Australia policy or enacting a native title regime."
Wong argued the only reason for a plebiscite being floated was for Abbott to avoid granting a free vote to Liberal MPs, and it is now being touted by marriage equality opponents as an opportunity to block progress.
"When social conservatives like the Australian Christian Lobby and Senator Bernardi are pushing for a plebiscite you know it is not because they want to achieve marriage equality – quite the contrary," she said.
Wong also expressed concern that a plebiscite would "operate as a license for hate speech", saying she does not trust conservative groups to behave responsibly.
"Opponents of marriage equality already use words which hurt and words that convey bigotry and prejudice," Wong said.
"We don't want our families, our children, our community to be exposed to prejudice, bigotry and hate – all in the guise of a 'debate' over marriage equality."
Referring to the recent failure in Houston, Texas, to enact anti-discrimination laws based on sexual orientation and gender, Wong said a conservative fear campaign demonising transgender people had contributed to the defeat.
"A fear campaign can ultimately win the day," she said.
"The Australian Christian Lobby use non-official websites and other material to twist the message of the Safe Schools Program for LGBTIQ young people in their campaign for its abolition," she said.
"It is hard to envision how organisations like this would behave responsibly in a national debate in the full glare of the media spotlight."