Former Queensland DPP Leanne Clare, who is now a district court judge, conceded that uncorroborated evidence and significant delays in reporting were common features of sexual assault claims, particularly from children, but she didn’t think the public understood this in 2002 when she decided not to pursue Volkers.

“At that time… the climate really was to acquit unless there was the strongest of evidence and this wasn’t that kind of case because it was uncorroborated and because of the delay,” she told the Royal Commission into Institutional Responses to Child Sexual Abuse on Wednesday.

“Back then, the delay was a greater burden to overcome than it is now because the general public has a better understanding of delay as a common feature of these kinds of cases.”

Volkers, who now lives in Brazil, was a coach with the Australian national swimming team and head of swimming at Queensland's Academy of Sport until 2002, when he was charged with indecent treatment of three girls in the 1980s.

It took more than a decade for the girls to make complaints and there were no other witnesses to corroborate their accounts, the commission heard.

Justice Clare dropped the charges in 2002 but, after a public outcry, the decision was investigated by the Crime and Misconduct Commission, who heavily criticised the DPP's reasoning.

The police re-opened the case and referred the charges to the DPP yet Justice Clare dismissed the case again in 2004 after seeking advice from NSW DPP Nicholas Cowdery and Crown Prosecutor Margaret Cunneen.

Ms Cunneen believed the allegations were “trivial” compared to other sexual assaults and she described a doctor’s view that one victim’s depression was caused by Volkers’ assaults as “almost fanciful”, the commission heard.

On Wednesday, Justice Clare said it was a “borderline matter” but she stood by her decision not to pursue Volkers.

“I have no doubt that that was the right decision at that time, that it was a reasonable assessment of the climate in which we were working back in 2002-2003,” she said.

Commissioner Justice Peter McClellan challenged her decision, suggesting that she would have known in 2002 that delays in making complaints and uncorroborated statements were common features of child sexual assault claims.

“Even in 2004 you knew that children very often didn’t make complaints until they were adults?” Justice McClellan asked.

“Yes,” Justice Clare replied.

“You... knew of that delay as being a common feature?”

“Yes.”

“You also knew that this sort of case very often lacked corroboration. It was just the complainant’s evidence against the defendant’s evidence?”

“Yes.”

Justice Clare conceded that she used the term “stale” to describe the historical charges and she apologised for showing Ms Cunneen’s reasoning to one of the victims.

"It was a mistake, there [is] no other way of saying it,” she said. “I should never have shown her the advice… and it clearly would have caused distress.”

The commission's hearing into Swimming Australia’s response to allegations of child sexual abuse concludes on Wednesday.

Justice McClellan will hand down his findings at a later date.