Julian Leeser, the re-elected Liberal member for Berowra, expressed surprise and concern about the surge in informal votes through the special hospital network.

He noted that in his electorate, the number of locations visited by the teams had increased from just four at the 2022 election to 31. Polling by the three teams was carried out over the entire pre-poll period rather than on a single day.

Leeser said the concept of special hospital teams was important as they sought to ensure all people, no matter their circumstance, had a chance to vote. But scrutiny of the way votes are declared informal was needed, especially if a person had indicated a clear preference for a particular candidate.

“If preference is clear, even if they haven’t filled out all boxes, then let the vote stand. They might just mark down one, or they might fill two or three or four boxes, but you can see the intent of the person,” he said.

“We don’t want people disenfranchised.”

Nationals MP Darren Chester, who sat on parliament’s joint standing committee on electoral matters, which reviews every election, said voters had raised concerns about the possible pressure put on people who may be suffering from dementia to cast a vote.

He signalled the joint standing committee had to examine the high informal vote.

“The large increase in informal votes collected in special hospital teams is clearly an issue that [the joint standing committee on electoral matters] needs to look closely at,” he said.

“Several voters raised with me their concerns about loved ones and their ability to cast a legitimate vote, and we need to look at that as well.”

High informal vote rates are often associated with large populations of voters from non-English speaking backgrounds, poorer or less educated voters or in seats with a large number of candidates. The rate of informal votes cast through special hospital teams is usually close to or slightly higher than the wider informal rate. This year, 5.6 per cent of votes were declared informal at the election, a marginal increase of 0.4 per cent on the previous election.

The south-western Sydney seat of Werriwa, comfortably won by Labor’s Anne Stanley, had the nation’s highest informal vote at 17.2 per cent, increasing 7 per cent from the 2022 election. In the electorate’s sole hospital team, the informal vote jumped by 14.6 per cent to 20.2 per cent.

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Informal votes cast through special hospital teams could also be a factor in other close results, such as the Victorian seat of Goldstein, and where there have been large numbers of preference flows between multiple candidates, such as the seat of Calwell.

An AEC spokesperson said the commission would conduct a study of the informal ballots, adding it was unclear on the reason for the spike in informal votes through hospital teams.

“We are unable to identify a specific reason for the higher informality rates in specific mobile voting teams at this time. This is in part due to the right to a secret ballot that Australian voters have,” the spokesperson said.

The planned study will examine all forms of voting, including ballots received through special hospital teams.

The spokesperson said there had been no change in the instructions that staff were directed to provide to voters. There was potentially a greater chance for confusion at mobile polling, such as that provided to people in residential aged care facilities.

“There is a process for families and representatives of people who no longer have the capacity to understand the voting process to apply to have these individuals removed from the electoral roll. This can be a serious and confronting step, and is not something we take lightly,” the spokesperson said.

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