Scott Morrison has his hands tied on extra coronavirus aid for Victoria

Scott Morrison would face a series of constitutional roadblocks if he attempted to mount a large-scale intervention to help Victoria.

Scott Morrison in Sydney on Monday. Picture: Damian Shaw

Scott Morrison would face a ­series of constitutional roadblocks if he tried to mount a large-scale intervention to stem the Victorian coronavirus outbreak.

The Prime Minister on Monday said his job was to support Victorian Premier Daniel Andrews’s Labor state government, with an ­escalation in the commonwealth’s role in ­addressing the Melbourne outbreak appearing unlikely.

If he were to change course, legal experts and federal government sources said the Con­stitution would prevent him from allowing the Australian Defence Force to enforce state lockdowns.

“The federal government has just one job and that is to support the Victorian government in all of these initiatives,” Mr Morrison said. “That is why there’s more than 1400 ADF personnel in Victoria right now, supporting across a whole range of tasks, to give Victoria every effort, ­resource that they need to get on top of this.”

The ADF personnel are assisting the Victorian government in contact tracing and managing the NSW border closure.

Calls for federal intervention from business and the state Liberal opposition have been partly fuelled by concerns over the time to receive results of tests.

The royal commission into the summer bushfires is investigating when and how the federal government can intervene in natural disasters — traditionally a state government responsibility — and the constitutional boundaries of the commonwealth’s power to act.

Mr Morrison said those findings could have implications for how his government could intervene in state handling of the pandemic, but he would not prejudge the royal commission.

“The royal commission is looking at that (constitutional boundary) in the case of natural disasters, and pandemics and natural disasters are, can be, one and the same thing,” he said.

“If not, they are very close cousins, that is for sure. There will always be lessons out of all of this.”

University of Sydney constitutional law professor Anne Twomey said the legality of any commonwealth intervention into Victoria would depend on the form of that action, and the expanded use of the ADF would be particularly difficult.

“The commonwealth does have quarantine powers and quite expansive powers under the Biosecurity Act,” she said.

“But the commonwealth can’t direct a state public service … they have no power over state police.

“The ADF’s role in state aid is very complex … under the Constitution, the ADF can have a role in defence and dealing with internal violence … otherwise they only have the powers of any ordinary person.’’