Australia's Disability Discrimination Commissioner Graeme Innes is also urging the Northern Territory and West Australian governments to audit their prisons to see how many people like Ms Fulton are incarcerated.
"These situations are in breach of the conventions against torture, the convention of the rights of people with disabilities and the declaration on the rights of Indigenous persons to name only three and there are probably a couple of others as well," Mr Innes said.
The Human Rights Commission said Ms Fulton needs to be released immediately so she can return to Alice Springs and receive appropriate care.
Ms Fulton has been in a West Australian prison for the last 18 months. She was arrested but never convicted over offences relating to a motor vehicle.
She suffers from foetal alcohol syndrome and a judge deemed her mentally unfit to stand trial.
The Commission said Aboriginal people like Ms Fulton are being kept in prison indefinitely because there were not adequate care facilities for them.
Mr Innes says an audit needs to be conducted to determine how many mentally ill inmates are being held without convictions.
"An audit would mean we'd know exactly how many people there are and at the moment that's quite unclear and once the audits carried out, it will give the governments a list of people whose circumstances need to change," Mr Innes said.
But the commission has said it can't force the release of prisoners like Ms Fulton.
Mr Innes said this was unacceptable.
"This is not an isolated case. There are somewhere between 30 and 50 people with disabilities, mainly Aboriginal people, who are incarcerated in prisons mainly in Western Australia and the Northern Territory without having been convicted of a crime and that is just an unacceptable situation," he said.
Mr Innes has written to the governments of the Northern Territory and Western Australia asking them to take action.
He said he's yet to hear back from either of them but is hoping to meet with the officials from both governments in the next few months to resolve the case.