A scathing review of tools used by Australian authorities to measure the risk posed by terrorists once they have completed their prison sentence has been made public after being kept hidden for years.
The Department of Home Affairs refused repeated calls to release the 2020 report, authored by ANU academic Emily Corner, after it was first revealed to criticise the two tools, known as VERA-2R and Radar.
The calls were refused on the grounds the report contained sensitive information that convicted terrorists could use to "manipulate" outcomes of risk assessments.
Now the report has been made public, released to the ABC and others under Freedom of Information laws.
The tools are used to measure the threat posed by people considered at risk of carrying out violent extremism.
Convicted terrorists can be held in detention after the completion of their sentence on "continuing detention orders" if they are deemed an unacceptable risk of committing another offence.
The first person to be held after their sentence on such an order was Abdul Nacer Benbrika, who later lost a High Court challenge to the validity of the law.
The VERA-2R tool was used by Australian authorities to determine the risk Benbrika posed to the community should he be released.
In total, it has been used by authorities on 14 different occasions — all of which happened after the Corner report was handed to Home Affairs in May 2020.
Home Affairs has been heavily criticised by figures including the Independent National Security Legislation Monitor, Grant Donaldson, for refusing to hand over the Corner report during Benbrika's legal challenge.
"Dr Corner's report should have been provided to Mr Benbrika … there is no excuse for not doing so," he said in a recent review of the terror laws.
The review called for continuing detention orders like that being used to detain Benbrika to be abolished.
Late last year, Mr Donaldson read excerpts of the report, which he had obtained but could not release, to a parliamentary hearing.
'No better than chance': Report questions usefulness of tools
The now-public 150-page report raises substantial doubts about the tools, and whether they can be relied on to accurately predict the risk an individual might pose.
"The lack of evidence underpinning both instruments has potentially serious implications for their validity and reliability," it finds.
"Without a strong theoretical and empirical basis for factor inclusion, it is not reasonable to anticipate that the instruments are able to predict their specified risk with anything other than chance."
The report is highly critical of the depth and breadth of research the two tools rely on, and argues there is not enough evidence to suggest the tools are particularly useful.
"The theoretical and empirical evidence base cited in the instruments' user manuals and supporting documentation is of poor quality, and is predominantly composed of theoretical assertions, secondary citations of literature reviews, and media articles," it says.
It recommends that those who designed the instruments urgently conduct a "far more thorough" review of available research on risk factors that can help predict a person's trajectory towards radicalisation and terror violence.
Greens senator David Shoebridge said the secrecy around the Corner report was unwarranted.
"I welcome the belated public release but it should never have been kept secret, let alone from individuals and their lawyers who were being detained on the basis of the VERA-2R assessment tool," he said.
"It is remarkable any court had ever accepted VERA-2R as expert evidence.
"It shows a tragic lack of thorough inquiry by the courts or prosecuting authorities before relying on this tool to keep people detained."
He said the saga surrounding the VERA-2R should raise further concerns about the use of continuing detention orders and similar legal tools.
"This shows the danger of speculating about future crime, a task which our criminal justice system has previously refused to undertake," he said.
