Liberal senator David Fawcett has warned a bill to recognise overseas same-sex marriages could open the door to Australia having to accept child marriages.
The 2014 Greens bill, brought forward for debate in the Senate on Thursday morning, would remove the part prohibiting the recognition of overseas same-sex marriages in the Australian Marriage Act, and recognise the marriages under Australian law.
The current patchwork state laws were brought to international prominence in January after the tragic death of David Bulmer-Rizzi, on honeymoon in South Australia with husband Marco.
As overseas same-sex marriages are not recognised in SA, David's death certificate was initially marked "never married", and Marco was bypassed for David's father on decisions surrounding the death of his husband.
Fawcett said there are many types of marriages not recognised in Australian law – including same-sex marriages, marriages where both parties do not consent, and marriages involving children.
"If we start making changes against our sovereign law in the interests of one group then why not the other groups?" he said.
"If we're going to be consistent... then we need to start recognising things like child marriage, which I think clearly Australians would reject."
Senator Cory Bernardi also warned that the door would be opened to polygamy.
"In some countries, you can go to Saudi Arabia or some of the Islamic countries where it’s legal for a man to marry four wives. That is a legal marriage. Should we recognise that in this country?" he asked the parliament.
Speaking in support of the bill, senator Janet Rice talked about her own marriage to wife Penny.
“I was married in 1986. In fact, my wife Penny and I will celebrate our 30th wedding anniversary next month," she said.
When they got married, it was "totally non-controversial," Rice said. But after Penny came out as transgender, society saw their marriage differently.
"She is now Penny. She was Peter in 1986. We were the same two people. We still loved each other. But suddenly our marriage was not considered the same as it was for the past 16 years," she said.
In most Australian states, transgender people must get divorced before they can change the sex on their birth certificate.
"She’s not going to do that, because we want to stay married," added Rice.
Senator Robert Simms, who brought the bill forward for debate, said it was an "absurd reality" that the government not only denies same-sex couples the right to marry here, but overseas as well.
"No-one should ever have to go through the trauma experienced by Marco Bulmer-Rizzi after his husband David’s death last month."
After Marco Bulmer-Rizzi's story received international attention, South Australian premier Jay Weatherill apologised and promised reform to recognise overseas marriages would be introduced by the end of the year.