Victoria's Royal Commission into Construction Corruption Begins First Open Hearing in Melbourne

The royal commission into corruption in Victoria's construction sector has begun with its first open hearing in Melbourne.

The hearing, in the Melbourne Magistrates' Court, is expected to address the inquiry's terms of reference and next steps before witnesses are called at later hearings.

Ben Carroll called the royal commission in his first act as premier in July, promising an exhaustive inquiry into the corruption allegations "as soon as possible".

Mr Carroll unveiled the inquiry's terms of reference in August, describing them as expansive.

"The terms of reference are broad. They are expansive. Nothing is off limits," he said at the time.

They include the extent of corruption on major infrastructure projects, the effectiveness of oversight from government bodies and actions contractors took to mitigate risks.

Former South Australian Supreme Court chief justice Christopher Kourakis is heading up the commission, which has a budget of $50 million.

In August, Mr Kourakis said the commission would be looking at issues "very important to all Victorians".

"I am deeply conscious of the responsibility with which I have been entrusted," he said in a statement released through the Department of Premier and Cabinet.

"The royal commission will undertake its work independently and rigorously. We will follow the evidence and ensure our processes are fair, thorough and transparent."

Mr Carroll committed to the royal commission after toppling his predecessor Jacinta Allan, who had long refused to call an inquiry despite internal pressure.

The Victorian opposition has persistently criticised the terms of reference, saying they allowed former premiers Daniel Andrews and Jacinta Allan to avoid being hauled before the commission.

However, Mr Carroll rejected the suggestion Ms Allan or Mr Andrews would not be called, having confirmed that ministers and former premiers would be fair game under the terms.

"Anyone and everyone can be called. These are the most comprehensive, broadest terms possible," he said in August.

"We're going to make sure that we leave no stone unturned."

The royal commission comes after an explosive report into the CFMEU released by the Queensland Commission of Inquiry in February.

In it, author Geoffrey Watson SC alleged the Victorian branch of the CFMEU descended into a "violent, hateful and greedy rabble" under former boss John Setka.

Mr Watson estimated that the actions of the CFMEU had cost the Victorian taxpayer around $15 billion — a figure that was strongly disputed by Ms Allan at the time.

Mr Watson said the terms of reference for the royal commission were "really excellently done" and he dismissed criticism by the Victorian opposition.

"I think they're very well designed, quite targeted, and sufficiently specific," he said.

"I think it's a mistake for people to go out and start undermining confidence in the commission before it starts.

"After all, this is a process through which we're hoping the confidence in government will be rebuilt. Now, why criticise it at this time? I do not know why, and I might make another point: the criticism is incorrect."

The commission is expected to report to the state government by August next year.