A radical shake-up of South Australia's court system, including the merging of the district and supreme courts, could be in the pipeline, a budget estimates hearing has been told.

South Australian Attorney-General John Rau said it might make sense to merge the two courts and create a separate appeals court.

He said many of the functions of the Industrial Court have also been taken up by new federal work laws and the South Australian Civil and Administrative Tribunal.

"There's a whole bunch of issues around the way in which the courts are functioning, and the question is, is there some way they can be better configured to give us all better value and get a more efficient justice system," he said.

SA Deputy Liberal Leader Vicki Chapman said talk of a restructure was a distraction from existing problems in court.

She said the system had been put under strain by vacancies on the benches of the district and supreme courts.

"At this stage the Government, and the Attorney-General in particular, is attempting to suggest that a restructuring of the court in some way is going to assist the efficiency of the court process," she said.

"It may, but in the meantime, these vacancies are there and they desperately need to be filled."

Ms Chapman pointed out that the hearing also heard there was no funding on the horizon for a courts upgrade.

"The Attorney-General holds multiple other portfolios, and is in a position to make this happen," she said.

Inaction on SA's court precinct upgrade not an option: Rau

Earlier today, Mr Rau said "doing nothing" was not an option for a stalled upgrade of Adelaide's court precinct.

The planned upgrade was abandoned earlier this year, despite the State Government admitting there was no question that the physical infrastructure of the supreme and district courts needed considerable investment.

The buildings are run down, with poor disability access and outdated IT facilities.

Mr Rau said he wanted to continue, through the budget process, "to agitate for a substantial investment in the courts".

"However, as everyone would appreciate I hope, I am but one of a number of ministers, all of whom have their own priorities," he said.

"These things are ultimately a Cabinet decision."

The Government had planned for a new $500 million courthouse to be built at Victoria Square in the city's CBD.

Three groups of companies had put forward proposals to fund and build the courts precinct under a model where the Government would agree to rent the courtrooms on a long-term lease.

The view across Victoria Square and city buildings of Adelaide from the courts precinct. ( ABC News: Matthew Doran )

Construction was meant to start early this year, with the precinct expected to be up and running in 2017.

The Government later decided the proposal did not offer value for money and would not be a "responsible allocation of taxpayers' funds".

Mr Rau told the estimates hearing there was "no provision for further progressing" the new courts precinct.

"[But] ultimately it's not that many years into the future where something must be done," he said.

The estimates committee also heard that the Government had set aside $6 million over two years for its nuclear royal commission, which it is undertaking to inquire into uranium enrichment, waste storage and power generation.

The State Government has asked the Commonwealth for a contribution.

Mr Rau said if the royal commission cost more than $6 million and there was no additional federal contribution, he would have to go back to Cabinet to increase the budget.