Did government jump the gun with mass detainee release?

The stateless man had served a jail term for sexually assaulting a child.

On his release, his Australian visa was denied. With nowhere to go, he was locked up indefinitely in immigration detention.

But the highest court in the land declared his detention unlawful and within hours, he was released.

About 140 others followed, among them murderers, sex offenders and a contract killer.

The ensuing political storm dominated Canberra.

The coalition said the November 8 decision ordered the release of NZYQ only, and that it wasn't until the court's full reasoning was released 20 days later that the government was required to free others.

"The government could have used the time between 8 November and 28 November to put legislation in place to keep Australians safe," coalition MP Paul Fletcher argued.

Michaelia Cash, the shadow attorney-general, described the decision as "baffling" and questioned why murders and rapists were released "before the High Court had even had a chance to put pen to paper".

The government's response has been blunt: it had followed the High Court's decision - and anyone in the same position as NZYQ had to be released without delay.

AAP asked some of the country's top legal academics for their perspective.

Anne Twomey, a constitutional law expert at the University of Sydney, said that while the order did only specifically direct the release of NZYQ, it meant any others in the same category were also being held unlawfully.

"The test for identifying this category has long been known and was relied upon during the proceedings before the court," Professor Twomey said.

"This is the test that there is 'no real prospect of the removal of the non-citizen from Australia becoming practicable in the reasonably foreseeable future'."

Monash University constitutional law professor Luke Beck, agreed, stating that the High Court was "explicit" about its reasons for NZYQ's release.

"The government knew that other people were also in the situation ... it would not have been lawful to keep those people detained."

In accusing the government of acting before it was required to, the coalition has referenced arguments made by Chris Merritt, the vice president of the Rule of Law Institute of Australia.

Mr Merritt argues the government was under "no obligation" to release anyone other than NZYQ before the court's reasonings were released.

"For 20 days until November 28 it was impossible to be certain about the central principle - or ratio decidendi - of the case", he said.

"It is to be found in the judges' reasons, not in their orders. The ratio is the only aspect of a High Court ruling that amounts to binding law.

"Without the ratio, there could be no legal certainty about the scope of the principles that underpinned the court's orders freeing NZYQ."

But UNSW constitutional law expert George Williams said it is the order of the court that is all important.

"The fact that the court's reasons had not been delivered was irrelevant. What matters is the order of the court, and that had been handed down," Prof Williams said.

"The key part of the High Court decision is its orders, which express the legal effect of the court's decision. The reasons explain why it has delivered those orders."

Prof Williams said that as long as it was clear the order applied to others, then they must be released.

"Not doing so would have opened the Commonwealth up immediately to an action from other people seeking the same effect as the order."

Melbourne Law School's Scott Stephenson said from November 8, it was all but guaranteed the order would apply to others.

Given the seriousness of unlawful detainment, he believed it wasn't unreasonable for the government to have acted immediately.

"That is the problem with the alternative view ... it implies that the government is free to curtail one of our most important rights, liberty of the person, when there are serious doubts about the validity of that curtailment," he said.

Australian Associated Press