Australia same-sex marriage vote can proceed, court rules
A vote on legalising same-sex marriage in Australia will proceed after a court dismissed two legal challenges.
The non-binding survey to gauge support for changing Australia's Marriage Act is due to begin next week.
The High Court of Australia dismissed separate objections by same-sex marriage advocates, who had argued the postal vote was invalid.
The survey does not have the power to make same-sex marriage legal, but it could lead to a vote in parliament.
Prime Minister Malcolm Turnbull has said the law could change this year if the vote shows majority support.
"We encourage every Australian to vote in this survey, to have their say," he said on Thursday.
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The voluntary survey has drawn controversy over its A$122m (£75m; $97m) cost and fears that it will prompt hate-filled campaigns.
Australians will have from Tuesday until 27 October to cast their vote. The results are expected to be announced on 15 November.
A green light to a complex process
Hywel Griffith, BBC News Sydney correspondent
After years of political procrastination, it looks like Australia should finally decide by the end of the year whether the law should change.
Both Yes and No campaign teams will now turn up the volume in a debate that has already become heated.
The opinion polls suggest a Yes vote will prevail - but then, as Britain's Brexit vote showed, it's wise not to try to second-guess the public.
The real question is what happens after the survey results are announced in November.
Will MPs be bound to follow the views of their electorate? Will they have to follow the party line?
The Attorney-General, George Brandis, has confidently predicted that same-sex marriage will be legal "by Christmas", but I expect a few more twists and turns along the way.
Those challenging the survey had argued the vote was invalid because it was not approved through parliament. They also claimed that the Australian Bureau of Statistics did not have the authority to oversee the process.
The arguments were unanimously dismissed by the court, which will release its reasoning later this week.
A lobby group behind one challenge said it would now devote its efforts to campaigning.
"Now we get out there, and we campaign long and hard for a Yes vote that we hope will reflect the will of the country," said Australian Marriage Equality spokesman Alex Greenwich.
Campaigners against change welcomed the court's decision.
"[The other side] have done everything they can to stop the Australian people from having their say," said Lyle Shelton from Coalition of Marriage.
"I am confident in the judgement of the Australian people."