Now Kate's friend threatens to sue Christian Porter

In walking away from his defamation action against the ABC, cabinet minister Christian Porter has opened a fresh round in the battle over the allegation of historical rape against him by a now-deceased woman, known just as Kate.

Jo Dyer, a friend of Kate – whose claim Porter denies – on Tuesday threatened to sue him, accusing him of impugning “my honesty and integrity”.

There is also now a battle over the settlement concluded between Porter and the ABC.

The federal court has yet to ratify the settlement, which involves expunging from the court record part of the ABC’s defence in the defamation case. But news organisations are seeking to have the material made public.

Justice Jayne Jagot said on Tuesday the issue might not be a matter for the parties. “There has to be a reason for the removal of a document from a court file,” she said. “It’s not done just because a party wants to do it.”

If a document is removed from the court file, there cannot be applications to see it.

ABC journalist Louise Milligan, who Porter also sued in his case against an ABC article reporting the accusation without naming him, tweeted on Monday “We are still absolutely committed to the 27 redacted pages being in the public domain”.

Dyer brought the successful legal action that resulted in Porter’s high profile barrister Sue Chrysanthou being prevented from appearing in the defamation case because of a conflict of interest.

Dyer said in her statement her lawyers had sent a second “concerns notice” to Porter over his “continuing defamatory comments”. “He should be on notice that if I launch legal proceedings, I tend to see them through to their conclusion,” she said.

She alleged two defamations by Porter. She said that on May 12, he implied her legal proceedings were “part of an improper last minute legal strategy to disrupt his now discontinued action”.

“He did this despite knowing the real reason for the court action, and the lengths to which I had gone over the preceding two months to avoid court,” she said.

“Yesterday Mr Porter alleged that, after ‘coaching’ from Ms Milligan, I had destroyed important communications that may have had a bearing on his now discontinued action against Ms Milligan and the ABC.

"This is absurd. As I stated in court under oath, a number of people, of whom Ms Milligan was but one, encouraged me to treat all communications about our dear friend Kate, and the allegations she made against Mr Porter, with the care and respect she and they warranted.

"I endeavoured to do so by both filing and deleting correspondence between me and other individuals as appropriate.

"There was nothing improper, illegal or sinister in my decisions to save or delete certain messages, decisions that were taken well before Mr Porter launched his now discontinued action against Ms Milligan and the ABC.”

Dyer said the allegations Kate made against Porter “remain completely untested. Until they have been investigated, it is untenable for Mr Porter to remain in cabinet.”

Shadow Attorney-General Mark Dreyfus said an independent inquiry was needed into whether Porter was fit to continue as a cabinet minister. Dreyfus also said the ABC material should be publicly available.