CANBERRA, Australia >> Australians will be surveyed on their support for gay marriage from next week after the nation’s highest court on Thursday dismissed challenges to the government’s power to conduct the postal ballot without Senate permission.

Gay marriage could be legal in Australia by December if most Australians who take part in the ballot support the reform. But the lawmakers who could finally change the law within three weeks of the survey results becoming known would not be bound to accept the people’s will.

Gay rights advocates argued in an emergency hearing in the High Court that the government did not have the constitutional power to survey the public through a unique 122 million Australian dollar ($97 million) postal ballot.

The seven judges dismissed both cases argued by separate groups of rights advocates.

The government had already gone to the expense of starting to print the ballot papers, which are to be posted to more than 16 million voters nationwide from Tuesday.

Prime Minister Malcolm Turnbull welcomed the ruling and urged all Australians to take part in the survey, which will be declared on Nov. 15.

“Lucy and I will be voting yes and I will be encouraging others to vote yes, but … above all, I encourage every Australian to have their say because … I respect every Australian’s view on this matter,” Turnbull told Parliament, referring to his wife Lucy Turnbull.

Opinion polls show that most Australians want same-sex marriage legalized, but many advocates question how representative of Australian attitudes the postal survey would be.

Opponents of gay marriage support the survey, although some conservative lawmakers have said they would not change the law even if a majority of Australians wanted reform.

The litigants who failed to stop the survey in the court immediately urged supporters of marriage equality to take part.

One of them, independent lawmaker Andrew Wilkie, said the judgment “doesn’t change the fact that this is bad government policy.”

“To be spending the money the way they are is out of step at least with the community’s expectations about how they should govern this country,” Wilkie said.

Lyle Shelton, spokesman for Coalition for Marriage which lobbies against reform, said recognizing same-sex marriage would lead to restrictions on freedom of speech and religion as well as “radical gender education in classrooms.”

“We know that this is a political agenda that carries many things with it, and radical LGBTIQ sex education is just one of those things,” Shelton said, referring to lesbian, gay, bisexual, transgender, intersex and those questioning their sexual identities.

The survey was the second choice of Turnbull’s conservative government that had promised a rare, compulsory vote known as a plebiscite. But the Senate refused to approve the AU$170 million ($135 million) for such a vote.

Market researchers have said that telephone opinion polling could more accurately gauge the public’s view on gay marriage in each of Australia’s 150 electoral districts for around AU$1 million — a fraction of the survey’s cost.