Former ABS chief says if forms include no personal identifiers, as bureau promises, it will be hard to determine who has voted

This article is more than 3 years old

This article is more than 3 years old

The marriage equality postal survey is vulnerable to voter fraud because Australians will not be given individual identifiers by the Australian Bureau of Statistics, experts have warned.

The move to anonymise the process is designed to address concerns that if ballots included personal identifiers the ABS would be able to match Australians’ opinions on same-sex marriage with other personal information, in effect spoiling the concept of the secret vote.

But now the former ABS chief, Bill McLennan, and two privacy experts have warned if voters are not sent an individual identifier, the ABS will struggle to determine who has voted.

It comes as Malcolm Turnbull told reporters in Canberra the government’s policy would remain that no free parliamentary vote would be allowed without a national vote, even if the high court blocks the postal survey.

The director of privacy law practice Salinger Privacy, Anna Johnston, told Guardian Australia that if the ABS has the power to collect opinions on marriage as statistical information “they can use the results for data matching without any further limitations”.

Marriage equality postal vote to be challenged in high court by Andrew Wilkie and advocates Read more

Since the ABS now retains names and addresses Johnston said there was “nothing to stop the ABS matching your electoral roll data and your vote yes or no [in the marriage survey]”, even allowing them to match voters’ answers with census information.

On Thursday the ABS promised that the postal survey forms will include “no personal identifiers ... and all materials will be destroyed by the ABS at the end of processing”.

Johnston said the ABS was in a “catch 22” because creating an identifier would lead to significant privacy concerns but promising not to raises questions about “how they can protect against a rigged vote”.

“How can they check whether or not people have voted multiple times?”

Johnston questioned whether the ABS was entitled to use the electoral roll and would retain that information. McLennan said the ABS “has no powers to ensure that the right people are answering” surveys.

“After the question is mailed to 14 Smith Street, whoever picks it up and answers it, that’s who answers it.

“You don’t know who they are ... It’s just a matter of practicality, it’s not a statistical issue. How do you do it? Ask them for a birth certificate and watch them fill it out? Bugger that, it’s not possible.”

Monique Mann, co-chair of the surveillance committee of the Australian Privacy Foundation, said it would have been “incredibly problematic” if the ABS created an individual identifier for voters, because that would be “at odds with privacy rights necessary for a healthy democracy”.

On the other hand, without an individual identifier, Mann said there would be problems determining who had and hadn’t voted on the electoral roll. “If it’s just a mailout it’s difficult to keep track of who has filled them out.”

Independent MP Andrew Wilkie and marriage equality advocates Shelley Argent and Felicity Marlowe are due to formally launch their high court challenge on Thursday in Sydney.

Turnbull has effectively ruled out the government allowing a free vote if the challenge is successful.

Postal plebiscite on marriage equality would cost 'up to $122m' Read more

“Our policy is very clear,” he said on Thursday. “We will not facilitate the introduction of a private member’s bill on this matter unless the Australian people have given their support through a yes vote through this national vote that we are now undertaking.”

However, Liberal MP Warren Entsch has reserved his right to cross the floor, raising the prospect that Liberals in favour of marriage equality could still suspend standing orders to force a debate and vote.

Treasurer Scott Morrison has now officially directed the ABS to conduct the postal survey, and given Australians just two weeks to get on the electoral roll or to apply to. Voters will have to get on the roll or apply by 24 August to receive a ballot.

Greens leader, Richard Di Natale, has urged Australians to enrol “so they have the choice of voting in a postal plebiscite on marriage equality if one goes ahead”, suggesting the Greens are gearing up to fight a yes campaign rather than boycott the poll.

Labor targeted the Coalition in question time over the poll’s probity, with deputy leader Tanya Plibersek questioning whether electoral laws banning fraud, bribery and intimidation would apply.

Turnbull said the poll would be protected by laws banning mail tampering, interfering with the collection of statistics, or obstructing ABS officials in the conduct of their duty.

On Wednesday the acting special minister of state, Mathias Cormann, conceded on Radio National that the “normal electoral laws” would not apply because the Senate had blocked the bill for a compulsory plebiscite.

As a result, laws requiring campaign materials to be authorised and not mislead voters about the mechanism of voting will not apply.

The ABS directed questions about the integrity of the poll to Cormann’s office.