Christian Porter and barrister Sue Chrysanthou may have to pay $500,000 in legal fees to Jo Dyer

Christian Porter and his high-profile barrister could be forced to pay more than $500,000 in legal fees to a friend of the woman who accused the former attorney general of raping her three decades ago, a court has heard. Porter strenuously denies the allegation.

Porter’s defamation case against the ABC was dropped in May, but a separate case has continued to drag on, and threatens to cost the former attorney general $500,000 in costs.

In May, a high school debating friend of the woman at the centre of the case, Jo Dyer, successfully restrained Porter’s star silk, Sue Chrysanthou SC, from acting in the ABC defamation case over what she said was a conflict of interest arising out of a meeting between the two women in November last year.

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In June, Justice Tom Thawley ordered Porter and Chrysanthou to pay Dyer’s costs after the four-day hearing.

Thawley ordered both Porter and Chrysanthou to pay, but did not make a ruling about how or whether those costs would be shared. The costs order found both jointly liable for the costs, meaning the order could potentially be enforced against either of them.

Both Porter and Chrysanthou are seeking to have the costs claim reduced, and in a federal court hearing on Tuesday Chrysanthou’s barrister, Anne Horvath, said her client was seeking access to timesheets and invoices to challenge the costs claim.

“Without that sort of data we just can’t deal with the information because we don’t know who did what when,” Horvath said during the hearing. “We’re not able to interrogate it all.”

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Similarly, Porter’s barrister, Callan O’Neill, said “without the data … it’s not possible to look with any granularity to what occurred”. He noted that one of the lawyers acting for Dyer had worked 245 hours in 16 days.

During the hearing, Thawley revealed the extent of the claim, saying it was a “lump sum of $500-odd thousand”.

The costs complaint comes after Porter last month lodged an appeal against Thawley’s ruling restricting Chrysanthou acting in the case, despite having already dropped his defamation bid against the national broadcaster.

If the appeal is successful, he could potentially argue that Dyer should pay costs.