Indefinite immigration detention ruled unlawful in landmark Australian high court decision

<span>Photograph: Lukas Coch/AAP</span>
Photograph: Lukas Coch/AAP

Indefinite immigration detention is unlawful, the high court has held, in a landmark decision overturning a 20-year-old precedent.

The result overturns the case of Al-Kateb, which had authorised indefinite detention of non-citizens without a valid visa even in circumstances where it is impossible to deport the individual.

On Wednesday the chief justice, Stephen Gageler, said that “at least a majority” of the justices agreed that sections of the Migration Act which had been interpreted to authorise indefinite detention were beyond legislative power.

The home affairs department believes the result could trigger the immediate release of 92 people who cannot be returned to their country of origin, including refugees and stateless persons, with the detention of a wider cohort of 340 people in long-term detention also in doubt.

In the first case heard since Gageler was sworn in as the chief on Monday, the high court ruled in favour of NZYQ, a stateless Rohingya man, who faced the prospect of detention for life because no country had agreed to resettle him, due to a criminal conviction for sexual intercourse with a 10-year-old minor.

The high court declared that because NZYQ had been detained when there was “no real prospect of his removal from Australia becoming practicable in the reasonably foreseeable future” his detention was unlawful.

It ordered he be released immediately, with the commonwealth to pay his costs. Gageler said the court’s reasons for its decision would be published “in due course”.

In submissions, NZYQ’s lawyers had argued the court must choose between an interpretation of the law that detention must cease if removal was not practically possible, or accept that “if it never becomes practicable to remove the detainee, the detainee must spend the remainder of his or her life in detention”.

Although NZYQ lost on the interpretation of the Migration Act, he won a separate constitutional argument that indefinite immigration detention breaches the separation of powers between executive government and the judiciary because it is punitive.

NZYQ’s case was supported by the Australian Human Rights Commission and the Human Rights Law Centre.

HRLC acting legal director, Sanmati Verma, said that “indefinite detention ends today”.

“This has life-changing consequences for people who have been detained for years without knowing when, or even if, they will ever be released,” she said.

“The government must respect the constitutional limits of detention and act immediately to free people who have been indefinitely detained.”

In Wednesday’s hearing the solicitor general, Stephen Donaghue, appeared to accept this, arguing that people in NZYQ’s position – where it is not reasonably practicable to deport them in the foreseeable future – “will need to be released immediately into the community”.

The shadow attorney general, Michaelia Cash, called on the government to “explore all available options to limit the risk posed by problematic individuals”.

The Greens senator Nick McKim said the decision “puts the lie” to the claim that “no-one is being detained indefinitely in immigration detention”, and that “anyone being held in contravention of this ruling” must be released. The government is considering the high court’s decision.

Donaghue warned that such a ruling would trigger “undefendable” compensation claims and the release of “undesirable” people into the community.

Related: Australia asked six countries to resettle stateless Rohingya man after he began high court challenge, lawyer says

Donaghue said NZYQ’s visa was cancelled and he was detained “only” because “he raped a 10-year-old boy” but his detention was not punitive because he is being held “until” he can be deported.

On Tuesday, lawyers for NZYQ revealed the Australian government had attempted to deport him to six countries. All but the US had rejected the request, and Donaghue conceded it was “impossible to predict with confidence” whether he will ever be deported.

On Wednesday afternoon, Perry Herzfeld, another senior counsel representing the commonwealth, said there had been “direct” involvement by the home affairs minister, Clare O’Neil, who authorised a “no stone unturned” approach in finding a third country to resettle NZYQ. The immigration minister, Andrew Giles, had agreed, he said.

Herzfeld said the prospect of resettlement in the US was “not vague” or in the “hazy distance”, submissions the court appears to have rejected by finding NZYQ’s detention was still unlawful after the approach to the US.

Donaghue submitted that the four justices in the majority of Al-Kateb were aware of the “harsh” possibility of lengthy detention, including for stateless persons who cannot be deported.

Donaghue noted that the “more undesirable” a person is the “more difficult” it is to remove them, but argued against NZYQ’s submission that they should be released if deportation is not possible.

Donaghue submitted that the executive had the power to keep non-citizens out of the Australian community for “understandable reasons” including character concerns.

The home affairs department estimated 92 people were in such a position, he said, all but nine of whom had had their visas cancelled or refused for character concerns.

Those included 78 refugees with citizenship of another country who cannot be returned due to a “well-founded fear of persecution”, and 14 people who are either stateless or have “intractable” cases, such as an inability to identify the detainee or lack of cooperation from them or their home country.

Donaghue warned that if Al-Kateb were overturned, the commonwealth would be exposed to “inevitable” damages claims for false imprisonment. These claims would be “undefendable” in cases where the government conceded the people had been detained while it was impossible to deport them, he said.

When Gageler noted that it “could be for ever” that a person is kept in detention, Donaghue replied: “That is Al-Kateb,” which established the principle that detention can occur “until” the event of deportation.

“If ever,” Gageler added.