Investigators probing war crimes want access to sensitive information heard in closed court when Ben Roberts-Smith unsuccessfully sued newspapers alleging his involvement in four murders.
The judge who dismissed the former soldier's defamation claims ruling the reports painted a "substantially true" image of him as a war criminal will not decide if the investigators can access the documents, due to potential bias.
Mr Roberts-Smith's lawyers did not allege Justice Anthony Besanko was actually biased, just that he may appear that way to the hypothetical fair and reasonable observer, after he presided over more than 100 days of hearings before making his judgment in June.
They requested he disqualify himself from hearing and determining whether investigators from the Office of the Special Investigator (OSI), established to probe allegations of war crimes, can access sensitive court files and documents from the defamation proceedings.
Mr Roberts-Smith has not been charged with any criminal offence.
He has appealed the judgment of Justice Besanko, who ruled reports in the Sydney Morning Herald, The Age and the Canberra Times containing allegations he was involved in four murders while deployed in Afghanistan were substantially true.
The decorated ex-SAS corporal has always denied the allegations and appealed the decision in July.
Commonwealth lawyers submitted Justice Besanko could and should hear the their applications for access to the court's sensitive files and documents.
The OSI began operating in January 2021 to review findings of an inquiry into Afghanistan deployments and is working with the Australian Federal Police to investigate alleged breaches of armed conflict laws by defence force members between 2005 and 2016.
"Criminal offences of the kind being investigated are extremely grave and their thorough investigation is of national and international importance," Justice Anthony Besanko wrote in a judgment on Friday.
The Commonwealth has sought access to a list of pseudonyms prepared for the defamation proceedings, closed court transcripts and exhibits, and sensitive outlines of evidence among others.
An affidavit in support from OSI investigations director Ross Barnett said he had limited ability to disclose the details of investigations in an open and unclassified document.
"He is able to say that there is an overlap between the subject matter of the investigations and the subject matter of the defamation proceedings," Justice Besanko wrote.
The judge who eventually hears the Commonwealth's applications will have access to two confidential affidavits after Justice Besanko decided it should not be him.
"I have made a number of serious findings of fact and credit against (Mr Roberts-Smith)," Justice Besanko reasoned.
An ordinary, right-thinking member of the community "would consider (strongly) that such matters should be the subject of a criminal investigation" and that was enough to give rise to a potential perception of bias, he wrote.
He said the circumstances were unusual in light of the strong findings he made but he concluded another judge should determine the Commonwealth's application for access.
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