South Australia's first openly gay state MP says he is ready to mount a legal challenge to allow gay couples to marry overseas.
SA upper house MP Ian Hunter and his partner of 22 years, artist Leith Semmens, plan to wed in New York following the US state's legalisation of gay marriage.
However, the wedding hinges on Mr Hunter receiving a Certificate of Non-Impediment to Marriage (CNI) showing the couple meet the legal requirements to marry in that country.
Mr Hunter said the federal government's refusal to issue CNIs for gay couples wishing to marry overseas was "mean spirited".
"I don't want to wait till I'm 75 to get married," he told AAP on Monday.
"It (CNI) has no legislative weight ... so I can't see for the life of me how making those instruments available ... will cause any blowback.
"I think that it's petty and mean spirited."
Mr Hunter said he would mount a legal challenge if necessary.
"I hope the government sees sense and actually gives me my CNI, but if they don't I'll consider making an appeal through the Administrative Appeals Tribunal," he said.
"If they do see sense then I might propose to my partner again and head off to New York."
Mr Hunter, who is also a vocal advocate of gay marriage, said there were fears removing the bureaucratic block would open the "floodgates" for the recognition of same-sex marriage in Australia.
"CNIs have nothing to do with same-sex marriage in Australia," he said.