Greens senator Nick McKim says his party "welcomes" the recent High Court decision that Aboriginal Australians are not “aliens” for the purpose of the constitution and cannot be deported regardless of their citizenship status.

An Aboriginal man held in immigration detention for 500 days has been released this afternoon following a landmark High Court decision.

Lawyers for Brendan Thoms have confirmed the New Zealand-born father has been freed just hours after it was determined that he cannot be deported.

Maurice Blackburn senior associate Claire Gibbs said her client should never have been detained in the first place.

“Brendan has had 500 sleepless nights worrying he could be deported at any time, and that is now thankfully at an end,” Ms Gibbs said.

“He is very happy to have been released and to now be reunited with his family at long last.”

This morning, the High Court handed down a decision that declared Indigenous Australians are not “aliens” under the Constitution, after a test case brought on behalf of Mr Thoms and a second man, Daniel Love.

Both men were born overseas but each have a parent who is an Australian citizen. They both identify as Aboriginal Australians and Mr Thoms also holds native title.

But they spent time in prison for serious criminal offences and the government cancelled their visas in 2018 and sought to deport them – Mr Thoms to New Zealand and Mr Love to Papua New Guinea.

“This is a very significant decision today that has helped to clarify the law – it is now beyond doubt that Aboriginal Australians cannot be deported through the exercise of the aliens power,” Ms Gibbs said.

Mr Thoms spent 500 days in detention, which Ms Gibbs described as “a hefty price for a crime he had already served time for”.

“From the perspective of common sense, Aboriginal Australians should never have been placed in immigration detention and threatened with deportation from Australia, and today’s High Court decision has further reinforced this fact.”

Both men came to Australia as children but are Aboriginal and have a “proud family history here and a strong connection to the land”, she said.

“Both had well and truly served their time for crimes committed, yet they were punished twice with no basis for doing so.”

The 4-3 majority decision in the High Court represents a significant victory for Mr Thoms but the court was unable to determine whether Mr Love is Aboriginal, continuing his uncertainty.

In court last year, Stephen Keim SC, barrister for the men, said removing them from the country would constitute significant dispossession.

“What we say is, to interpret the ‘aliens’ clause in the constitution to say it’s all right to remove Aboriginal Australians from the country they have occupied for 80,000 years on the mere basis that they happen to be born overseas is another dispossession and raises similar challenges to that considered by the court with regard to Terra Nullius,” Mr Keim said.

Ms Gibbs said the government’s decision to detain the men “defied logic” and said today’s decision had exposed it as “unfair” and “wrong”.

“Significantly, today’s ruling is also a win for any other Aboriginal Australians in similar circumstances and we are very proud of this result,” she said.