Families of the victims of the Bourke Street massacre will find out if Victoria Police will be allowed to keep details of its new car pursuit policy secret from an inquest.
Police cars chased James Gargasoulas before he drove down Melbourne's Bourke Street Mall, killing six people and injuring dozens of others in January 2017.
Coroner Jacqui Hawkins will make a ruling about the police request at a hearing of an inquest into the deaths on Friday.
Victoria Police's lawyers argue Gargasoulas knew about the police no-pursuit policy at the time, so details of the force's new policy should remain confidential in the interests of public safety.
"When it became publicly known that police would back off from pursuing certain drivers ... that resulted in persons adopting that form of behaviour," Ian Freckelton QC argued.
He said police pursuit policies had "evolved" and changed "significantly" since the January 2017 massacre.
Dr Freckelton said police weren't seeking to suppress details of the pursuit policy at the time, which needed to be "fully canvassed" during the inquest.
But lawyer Sue McNicol QC, who is acting for the families of the deceased, argued against suppressing documents from publication.
"The reports are inextricably intertwined with the issues to be ventilated," she said.
"You cannot unscramble this egg."
Aine Magee QC, also acting for the victims' families, argued the inquest should be broadened to explore "whether there were opportunities that were lost" in preventing the massacre.
The one-month inquest, with 46 witnesses, will run from November 18 until December 20.
It will also investigate the justice system's treatment of Gargasoulas, including an out-of-session bail hearing that released him from custody just days before his deadly rampage.
However, the inquest will not consider the correctness of the bail justice's decision.
The murderer, who suffers paranoid schizophrenia, was handed a life sentence in February and will not be released for a minimum of 46 years.
