Senior lawyer Mark Leibler says the government must keep the question posed in a referendum simple, while educating people on what they are voting for.
The referendum will be about protecting a voice for an advisory body in the constitution, not the details of the body itself, he said.
"I support the idea of getting out to the public the kind of body that we have in mind, but that's a far cry from a detailed legislative model ... that's for the parliament, that's not for the constitution," he told ABC radio on Monday.
"If you leave people with the impression that this is what is protected by the constitution - in other words a model that's being introduced today and forever - it would be almost impossible to get a referendum through."
Mr Leibler said recognising Aboriginal and Torres Strait Islander people must be done in a way that meets their requirements.
"What's become fairly obvious is they want something that is both substantive and also symbolic, and that's the protection in the constitution we're talking about," he said.
"It's either that or nothing, because you can't recognise people in a way that they're not prepared to be recognised."
Former prime minister Tony Abbott earlier this month called for all the detail behind an Indigenous Voice to parliament to be released before Australians vote in a referendum.
But talk about veto powers, third chambers or interference with parliamentary processes is deliberate distraction, Mr Leibler said.
"There is a lot of confusion created deliberately by some people in terms of the details of the model," he said.
"It's just so simple and so easy. Not only that, in terms of its workability and how it's going to proceed ... is left entirely up to the parliament.
"I just don't understand why there should be any controversy whatsoever about this."
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