Former ACT Director of Public Prosecutions, Shane Drumgold SC, is alleging a Board of Inquiry report, which made scathing findings against him, was "infected" by apprehended bias.

His lawyers have claimed the relationship between the report author, Mr Sofronoff, and Janet Albrechtsen, a columnist from The Australian, caused this bias.

Mr Drumgold is seeking the report be quashed or, alternatively, the conclusions made in relation to him be declared invalid, or affected by bias, or a denial of natural justice.

It examined the now-dropped prosecution of Bruce Lehrmann, who has always denied raping fellow former Liberal staffer Brittany Higgins at Parliament House in 2019.

On Thursday, counsel for Mr Drumgold, Dan O'Gorman SC, told the ACT Supreme Court "the now known behaviour of Mr Sofronoff was so extraordinary in the circumstances" he couldn't find similar comparative cases.

"These exchanges highlight the private and secretive nature of some of the text messages," Mr O'Gorman said.

The court previously heard Ms Albrechtsen and Mr Sofronoff had 273 "communications" in a seven-month period, this included 51 phone calls.

Ms Albrechtsen also flew to Brisbane to have a private lunch with Mr Sofronoff, who recommended the restaurant.

"Nowhere is there any evidence to suggest that private communications of the type engaged by Mr Sofronoff and Ms Albrechtsen is appropriate," Mr O'Gorman said on Thursday.

Mr O'Gorman told the court the columnist was "a person with known views adverse to Mr Drumgold" and had written numerous "nasty" articles.

"Also present at that time were expressions of opinions that were supportive of Mr Lehrmann," Mr O'Gorman stated.

On one occasion, the inquiry chair texted Ms Albrechtsen saying: "Got a minute?"

Another time, the columnist messaged Mr Sofronoff asking if he knew when the DPP first met with Ms Higgins.

"I'll see if I can find out," Mr Sofronoff responded.

Mr O'Gorman said the familiarity of this phrasing was "of some significance".

"That is hardly the language that would be used by a commission chair to a journalist."

On Wednesday, counsel for Mr Sofronoff, Brendan Lim, argued there was "no preferential treatment".

Mr Lim stated Mr Sofronoff gave evidence in an affidavit that he had "engaged with any journalist who approached him".

"Ms Albrechtsen was the most persistent," Mr Lim said.

In an affidavit, Mr Sofronoff has claimed the phone calls were about "practical matters" including when documents would be made available and the timing of the inquiry.

The findings of misconduct in relation to Mr Drumgold include that he knowingly lied to Chief Justice Lucy McCallum and "preyed on" the inexperience of a junior prosecutor while dishonestly withholding documents from Mr Lehrmann's lawyers.

Mr Sofronoff also found Mr Drumgold at times "lost objectivity and did not act with fairness and detachment as was required by his role" during the trial.

Acting Justice Stephen Kaye is set to hand down his decision at a later date.

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