A wall painted with the rainbow flag and the message “Vote Yes!” in Newtown on Aug. 28 in Sydney. (Mark Kolbe/Getty Images)

Richard Glover is an Australian writer and broadcaster.

How should a country decide the issue of same-sex marriage? Most hold a referendum (Ireland, for example) or they leave it to a vote of their elected leaders (such as Germany).

In Australia, though, we’ve developed our own peculiar process. We’re going for a nonbinding, non-compulsory postal vote, which — for legal reasons — has to be dressed up as a survey.

People are now busy campaigning on both sides, with television commercials and heated arguments. The voting forms — sorry, survey inquiries — are due to arrive in our mailboxes in a couple of weeks. And yet the whole project may well be illegal: Australia’s High Court this week is hearing submissions as to whether the whole caper is unconstitutional.

Even if the High Court gives approval, the postal vote will still be a peculiar piece of policy. It will cost nearly $100 million (U.S.), even though its result can be ignored by Parliament, and — in terms of statistical accuracy — could be better achieved by a polling company at the cost of a few thousand dollars.

So, how have we come to this point? Australia, after all, is a gay-friendly country. Sydney stages an annual Gay and Lesbian Mardi Gras in which much of town, straight and gay, gets caught up in the excitement. Add in the opinion polls in which a thumping majority of citizens believe same-sex people should be allowed to marry: According to a recent poll, 63 percent say they will vote “yes.”

Even within Australia’s large Catholic community, polls suggest that two-thirds of the laity will defy the church leadership and vote in support of same-sex marriage.

So, why not a parliamentary vote like in other countries?

That idea was rejected by conservative forces within the government who feared that, given a chance, the parliamentarians would vote “yes.”

Australia’s prime minister, Malcolm Turnbull — the man who phoned President Trump in the “worst call by far” — is, by and large, a progressive leader in charge of a conservative party. He’s Canada’s Justin Trudeau, if Trudeau had decided to lead the Conservative Party of Canada.

The consequence: Turnbull must more-than-occasionally prove his loyalty to the right wing of his own party. Same-sex marriage — and the refusal to have a parliamentary vote — became a litmus test of his willingness to honor their views.

So, with a parliamentary vote was out, what next?

The conservatives said they were willing to offer a formal plebiscite. Like all Australian elections, it would be compulsory. On the basis of all available polls, the public would have voted “yes.”

But this method was also rejected –- this time by the same-sex marriage advocates. They feared a plebiscite — with its formal voting day and election trappings — would result in a divisive campaign, featuring TV advertising, leafleting and graffiti. Terrible things would be said about LGBT people and their families — a group already beset by prejudice.

They also argued that plebiscites are not really part of the Australian tradition. Our politicians get to decide on all sorts of life and death issues, so why should this be different?

That argument was accepted by the key opposition parties, with the result that the plebiscite was voted down in the Australian Senate.

This was not good news for the government. Not only is the party divided on the issue — Turnbull is himself a supporter of same-sex marriage — but it began to dominate the news, preventing the government from playing to its strengths on security and the economy.

The solution: the postal vote. Because it’s a “survey” and will be run by the Bureau of Statistics, the government believes it can itself authorize funding, without the approval of Parliament — a belief on which the High Court will need to pass judgment.

The “yes” campaign finds itself divided. Some talk of boycotting the vote, others of embracing the method, however wacky. In a country where voting is usually compulsory, the issue of turnout is — for once –important.

As a result, there has been a push to encourage young people to enroll. At the urging of the “yes” campaigners, 90,000 Australians added themselves to the electoral rolls — mostly, it is thought, the 18- and 19-year-olds who had only recently become eligible.

Most analysts believe the postal vote will result in a “yes” verdict and that the parliamentarians will then sign the result into law. If so, Turnbull will be able to let loose a sigh of relief, although not for long. The postal vote might have seemed like a clever piece of politics, but there’s a sting in the tail.

Come the next election, there will be a higher-than-normal number of 18-year-olds on the electoral role — and that’s a group more likely to vote Turnbull out of office.