Proposed Senate voting rules legally vulnerable and incoherent – experts

Proposed changes to Senate voting rules are incoherent and vulnerable to a high court challenge unless voters are allowed to number fewer than all the boxes “below the line”, an inquiry into the most sweeping electoral changes in 30 years has heard.

George Williams, a constitutional specialist, also called on Tuesday for a ban on parties encouraging voters to number a single box “above the line” – which under the proposed system would see a ballot exhausted should that chosen party lose.

The University of New South Wales professor said a high court challenge against the new rules was unlikely to succeed, but its chances would be “improved by the current state of the bill”.

“The discrimination between above and below the line voting is no doubt an argument that would be put in any high court challenge, in suggesting it’s an incoherent system that does not properly reflect the need to directly choose the representatives,” he said.

Under the bill, which is backed by the Greens and Nick Xenophon, voters would still be required to number every box if they vote “below the line”.

Group voting tickets would be abolished “above the line” in favour of optional preferential voting, where voters number their preferred parties, with advice to mark at least six boxes.

Williams told the half-day inquiry on Tuesday extra protections were needed to ensure the new rules did not become “a de facto vote one system”.

He warned that parties could produce campaign material encouraging voters to mark just one box, leading to higher rates of ballot exhaustion, or “confusion where there’s a difference between how to vote cards and advocacy, and the instructions on the ballot paper”.

A similar system in place in NSW sees around 80% of ballots exhausted before every box is filled, according to psephologist Antony Green.

Absent these changes the bill only did “half the job that is required to fix the system”, Williams said.

Green, who is also giving testimony, welcomed the changes, but said voters below the line should be permitted to fill fewer than all the boxes.

He said a system where voters could exhaust their ballot once they had run out of preferred candidates would more accurately reflect their intentions.

“You’re weighting it towards the preferences people have. If they don’t give preferences, they don’t have a preference, they don’t have a view on that sort of area,” he said.

It also weighted the system “towards those who campaign, who hand out how to vote cards”, rather than candidates who picked up preferences late in the vote count.

Green was also sceptical of concerns, voiced in Labor analysis leaked on Tuesday, suggesting the Coalition would be advantaged by the proposed changes, arguing it would “tend to produce the same thing as the current system”.

Earlier, the chief of the Australian Electoral Commission (AEC), Tom Rodgers, said the new voting rules could be implemented within 100 days, clearing the way for them to apply in a July double dissolution election, if one was called.

Rodgers told the inquiry the “three-month clock” would begin as soon as legislation was passed but “the AEC stands ready to deliver an election whenever the government call it with the legislation that’s in force at the time”.

The committee reports on Wednesday morning.