WorkSafe has been accused of using an inquest into the deaths of dozens of St Basil's Home for the Aged residents as a "dress rehearsal" for the prosecution of the home's management.
Chairman Kon Kontis and manager Vikki Kos have asked the Victorian Supreme Court to stop Coroner John Cain forcing them to give evidence at an inquest into the deaths of 50 residents in 2020.
The pair were running the home when 45 residents died from COVID-19. Another five residents died during an outbreak that began on July 9.
On July 22 the entire staff was replaced with an inexperienced emergency workforce which, within hours of the handover, struggled to care for the mostly Greek-speaking residents who missed meals and medication.
The duo's evidence would be subject to an order that anything they say cannot be used in a criminal prosecution against them.
But that wouldn't prevent derivative use of their evidence, their barrister Ian Hill QC said, raising concerns about witnesses tailoring their own evidence in accordance.
The fact WorkSafe was represented by two barristers on each day of the inquest indicated a real overlap between the inquest and any criminal proceedings, Mr Hill said.
Mr Hill also took issue with Judge Cain's decision in December last year to hear from families of those who died in an "extraordinarily informal" closed court hearing shortly before ruling that Mr Kontis and Ms Kos would have to give evidence.
He sat at the bar table with families and their lawyers and told them to call him John, Mr Hill said.
One family member accused Mr Kontis and Ms Kos of lacking courage, and of "negligence and incompetence" that led to the deaths of 50 people.
Another family member had earlier implored Judge Cain to require the pair to give evidence.
That occurred before Mr Hill's in-court submissions to the coroner but after written submissions were filed, he said.
The woman said grieving families trusted Mr Kontis and Ms Kos to care for their loved ones.
"If they do not take the stand it will be a final slap in the face for all of us," the woman said.
An alternative to forcing the pair to give evidence now would be to allow the criminal law process to take its course, either with charges to be laid or an announcement by prosecutors that they would not proceed with a criminal case, Mr Hill said.
The trial before Justice Stephen O'Meara is expected to take two days.