Home Affairs advised 'we would win': Clare O'Neil

As the fallout from the landmark judgement continues, Ms O'Neil told Sky that she had been assured by the Home Affairs Department that "it was likely that the Commonwealth would win the case".

Asked if the advice came from secretary Mike Pezzullo, who has stood aside while under investigation for possible code of conduct breaches, the minister declined to identify "which individuals give me advice about any of this".

The government's preparedness for the possibility of the High Court overturning the detention regime has became a political flashpoint, with Opposition Leader Peter Dutton accusing it of being derelict in not having drafted legislation ready to introduce in the event of such an outcome.

Opposition home affairs spokesperson James Paterson told ABC television it was "very clear [the government] was caught on the hop when the High Court handed down its ruling".

"It's very clear that they didn't have the legislation ready to introduce to the Senate, which was sitting ... and could have been introduced into the House on Monday of this week, and all of this could have been avoided," Senator Paterson said.

But Ms O'Neil defended the government's handling of the matter, arguing that the High Court's decision was unexpected.

The minister said the High Court's decision was "quite unusual" in overturning decades of legal precedent.

"The decision of the High Court was very significant," she said.

"It overturned a 20-year legal precedent which has governed how the commonwealth deals with immigration detention."

The minister confirmed that following the decision 93 people were released from immigration detention.

Legislation passed late last week creates a new visa category under which people can be closely monitored and face significant restrictions, including wearing ankle bracelets and being subject to curfews and onerous reporting conditions.

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Ms O'Neil said those released were "not people who I wanted on the streets in our country" and they were being case managed under a joint Australian Federal Police and Australian Border Force operation.

Ms O'Neil said the legislation setting up the new arrangements may require "some refinement" when the reasons for the High Court's ruling are released early next year.

But she rubbished Mr Dutton's call for the 93 to be brought back into detention.

"It is not possible. And I know the Peter Dutton knows that," she said.