One of two Indigenous men at the centre of an historic High Court ruling has confirmed he has been released from immigration detention, after it was found Aboriginal people hold a special status in Australian law.

The High Court has found Aboriginal people are exempt from immigration laws, after considering the cases of two men facing deportation for criminal convictions.

The two Indigenous men, Daniel Love and Brendan Thoms, have faced deportation since failing their migration character tests as a result of serving jail sentences.

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Brendan Thoms, with his mother Jenny.

In a 4-3 split, the High Court today found Aboriginal Australians were not subject to the alien powers in the constitution and could therefore not be deported under immigration law.

But the court did not clear Mr Love entirely, saying it could not reach agreement on whether he was an Aboriginal person on the facts stated in the case.

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Daniel Love with his family.

Both men were born overseas but moved to Australia as children and held permanent residency visas.

Mr Love, a recognised member of the Kamilaroi people but born in Papua New Guinea, was placed in immigration detention after being sentenced to more than a year in jail for assault occasioning actual bodily harm.

A delegate for Home Affairs Minister Peter Dutton had cancelled the 40-year-old's visa, but that decision was later revoked and he was released from detention.

Mr Thoms was born in New Zealand and also does not have Australian citizenship, though he is a native title holder as a member of the Gunggari people.

After serving part of an 18-month sentence for a domestic violence assault he was taken into immigration detention, where he has remained while awaiting the outcome of the High Court case.

Outside the High Court, one of the men's lawyers Claire Gibbs, said Mr Thoms had been in detention for 501 days and was "incredibly relieved" by today's judgement.

"That's 500 sleepless nights and we hope that is the last," she said.

"He's missed two Christmases with his family [and] one of his son's birthdays. His son's birthday is coming up again so he's hopeful of returning to celebrate with his family."

Ms Gibbs said today's High Court ruling was not about citizenship, but was instead about "who is an Australian national and who is a part of the Australian community".

"It's about the use of alien powers, which we believe the government has been using inconsistently, unfairly and, now we've proven, unlawfully," she said.

"So, in a practical sense, Brendan is still a New Zealand citizen, but he's not an alien in this country and he's protected from being deported.

"Aboriginal Australians can no longer be removed from the country that they know and the country that they have a very close connection with."

Ms Gibbs said while the High Court today did not make a determination as to Mr Love's "Aboriginality", she was confident lawyers could prove that was the case.

In an unusual move the High Court held two separate hearings into the case.

It was originally heard in May last year, but came back in December after the court suggested the parties consider whether Aboriginal people occupy a special position, backed up by common law recognition of native title rights.

If that was the case, the court said it then followed that the crown had a unique obligation to protect Aboriginal society, and in return Aboriginal people owed a permanent allegiance to the crown.

Lawyers for the men submitted that Aboriginal people could not be "alien" to Australia.

"Aboriginal Australians are a permanent part of the Australian community," they wrote in a submission.

The submissions also stated that at Federation, Aboriginal people were not considered "aliens" under the constitution.

But the Commonwealth told the court any person who was not a citizen was an "alien" under the law, and that Mr Thorns and Mr Love owed their allegiance to the countries they were born in.

-ABC