An embattled state Labor government could suffer bruising scrutiny under a properly armed royal commission but it sorely needs one to rebuild trust, integrity experts say.
After being sworn in as Victorian premier, Ben Carroll's first move was to call a royal commission into the construction sector.
It followed sustained pressure on his predecessor Jacinta Allan to investigate alleged corruption on taxpayer-funded Big Build job sites.
While details remain thin, Mr Carroll insists the inquiry's scope will be comprehensive and allowed to go after the government.
"No stone unturned," he told reporters on Wednesday.
"Whether it is top-tier contractors, subcontractors, labour hire, government, unions, these will be exhaustive terms of reference."
Integrity experts have welcomed the about-face, but warn the inquiry must be unflinching or it could risk harming, not restoring, an ailing Labor government.
William Partlett, associate law professor at the University of Melbourne and fellow at the Centre for Public Integrity, described the inquiry as a "crucial turning point" for Victoria.
"This could be the first step in starting to address this corruption scandal and allegations that are threatening our state government's legitimacy," he told AAP.
"It should have been done earlier, but I applaud the Labor government now for finally doing it."
The public would expect to see testimony from private contractors and government representatives, including Ms Allan and her predecessor Daniel Andrews, he said.
Among the loudest voices calling for a royal commission has been Geoffrey Watson SC, the barrister who oversaw a months-long investigation into the CFMEU.
The integrity expert's report estimated $15 billion might have been lost to wrongdoing on taxpayer-funded construction sites in Victoria.
Ms Allan long disputed that figure as "unfounded and untested" but refused to call an inquiry to examine its veracity.
"I said $15 billion, but I also qualified that by saying I had neither the qualifications nor the experience to get to the bottom of it," Mr Watson told the ABC.
"And what it required was, in effect, a royal commission. Now we've got that."
Mr Carroll has not detailed who would lead the inquiry but suggested hearings would start "as soon as possible".
A special prosecutor would work alongside the commission, he added.
Opposition Leader Jess Wilson trashed the announcement of the inquiry as a "sham" designed to win back votes.
"He's only doing it because the polling is telling him that Labor is going to lose too many seats," she said at parliament on Wednesday.
In addition, Mr Carroll has vowed to give Victoria's Independent Broad-based Anti-corruption Commission "follow the money" powers before the November election instead of in 2027.
IBAC commissioner Victoria Elliott has since written to the premier to stress the powers must be accompanied by other key legislative changes to ensure it has jurisdiction to investigate and expose concerning conduct involving public funds.
