Porter, who emphatically denies the incident happened, took action over an article about a now-deceased woman’s claim he sexually assaulted her decades earlier.
He was not identified in the February article but revealed he was the man at the centre of the allegation after social media speculation.
The two parties settled last week with the ABC agreeing to put an editor’s note alongside the online story, saying it regretted some readers misinterpreting the article an accusation of guilt against Mr Porter.
ABC managing director David Anderson said the cabinet minister offered to settle the action both before and after the broadcaster presented its defence.
Anderson said there was a difference between the two settlement offers but refused to detail the change.
“I don’t want to sabotage any possible mediation in the future by revealing what was in these without-prejudice offers that came before us,” he told a Senate estimates hearing in Canberra on Monday.
Porter accused the broadcaster of a humiliating back down after the agreement was reached, prompting the ABC to release another statement rejecting his claim it regretted the story.
“I, on behalf of the ABC, am not humiliated and we do not regret the article,” Anderson told the hearing.
The ABC managing director said both settlement offers were rejected before the mediation which resolved the case started.
“Both parties could see a way forward that would certainly minimise cost,” Anderson said.
“Had we gone through to trial it would have been extensive costs, it would have been a long trial and if the two parties could find terms it could agree on then it was worth pursuing.”
The ABC agreed to pay $100,000 in costs for the mediation process including half of the mediator’s $31,000 fee, which has been split between the two parties.
Anderson said ABC’s legal bills combined with mediation costs total about $780,000.
But he estimated a further hit to the broadcaster’s coffers of between $1 million and $1.5 million if there was a three-week trial.
Anderson also said he was concerned about Four Corners executive producer Sally Neighbour’s “factually inaccurate” and now-deleted tweet about the settlement.
Neighbour initially posted that no money would be paid by the ABC but corrected her statement after Anderson contacted news director Gaven Morris.
“On this occasion, I felt that needed to be corrected as fast as possible,” Anderson said.Jump to next article