Non-citizens unlawfully held in immigration will be able to sue the federal government for compensation following a "significant'" judgment by the nation's top court.
The High Court on Wednesday unanimously dismissed claims from the Commonwealth it had immunity from compensation claims brought by detainees.
The decision has paved the way for detainees to receive millions of dollars in compensation payments from the federal government.
The case was brought by Austrian citizen Safwat Abdel-Hady, who was held in immigration detention and his visa was cancelled on character grounds.
He later sued for compensation for his time in detention following a November 2023 ruling by the High Court in the NZYQ case, which found it unlawful to detain non-citizens when it was impossible to deport them.
The High Court's ruling on Wednesday could pave the way for more than 300 people who were released from indefinite detention in the NZYQ cohort to sue for compensation.
In the judgment, Chief Justice Stephen Gageler, along with justices Jacqueline Gleeson and Robert Beech-Jones, said immunity could not be granted to the Commonwealth when transgressions had occurred.
"To do so would amount to an inversion, if not a perversion, of constitutional principle," the ruling said.
"If accepted, the novel common law defence proposed by the Commonwealth would purport to confer protection on Commonwealth officers for unlawful acts they undertake."
A spokesman for the federal government said the ruling was being examined.
"The Commonwealth notes the decision of the High Court and is carefully considering the judgment and its implications," the spokesman said.
The Asylum Seeker Resource Centre welcomed the legal win, saying it extended far beyond Mr Abdel-Hady's case.
Its deputy chief executive Jana Favaro said it was a critical step towards justice.
"This is a significant outcome, because it paves the way for people to finally access justice for the cruelty inflicted on them," she said.
"This decision is not just about the years that have been taken from people, it is also about the harm that has been done to them during that time.
"No government should be able to unlawfully detain people and then walk away from the damage it has caused."
Opposition home affairs spokesman Jonathon Duniam said the court ruling was another disaster linked to the NZYQ decision.
"Taxpayers may now be exposed to tens of millions of dollars in further liabilities because this government failed to properly manage the legal and practical consequences of NZYQ," he said in a statement.
"The Albanese government should be responsibly protecting the community, sensibly managing the immigration system, and ensuring the Commonwealth acts lawfully.
"Every new legal consequence of NZYQ is a reminder of Labor's incompetence and weakness on border protection."
