Constitutional expert George Williams wants to see a permanent commission investigating and reporting to parliament priorities for reform.

"When it comes to constitutional reform, it's essentially a political debate, without any formalised process of expert involvement," he told AAP on Wednesday.

"What you have with the (Indigenous) voice debate is a live political issue but, in the absence of a commission, no roadmap or adequate vehicle for taking it forward."

There's been a push to change the constitution to recognise Indigenous Australians for decades.

A constitutionally enshrined Indigenous voice to parliament was recommended in the 2017 Uluru Statement from the Heart.

The coalition wanted to legislate a voice to government instead.

It initially committed to introducing a bill before the election, now expected in 2022, before walking back on the timeline.

The attorney-general's department maintains the federal government's priority for constitutional reform is the recognition of Aboriginal and Torres Strait Islander people.

But a concrete timeline remains elusive.

Professor Williams thinks a standing constitutional commission could help speed things up.

"If you had a body like this that really was representative and the body came forward and said 'we can see merit in this and this is how you could draft it in a safe, secure way', then having that put forward through a nonpartisan process can often be very powerful in cutting through a partisan debate," he said.

"The voice, of course, has largely transcended many of these processes - it's been around a long time, it's been widely debated. Nonetheless, a commission could still help."

Professor Williams also believes such a body - small, taking in experts, community representatives and people from different political backgrounds - could untangle problems around broader issues about how the federation functions.

He lists as examples difficulties in establishing joint state and territory regulatory bodies, resulting in multiple regulators and additional red tape.

Another is the divide between state and federal courts, with uncertainty about where a case can and should begin.

"We often have a really inefficient federal system with blockages and high expense - you expend a lot taxpayers' money," Professor Williams said.

"Many of (the reforms) are just about keeping the document up to date so that our system of government works efficiently and well and in a way that serves the community as it should."

He is due to speak at a lower house inquiry on Monday looking at reforms to the constitution and referendums.

"We have a very old document that is absolutely fundamental in determining how this country is run. Yet we just don't have processes or people who are looking at it holistically to bring forward needed reforms."

Australian Associated Press