The former independent monitor of Australia's national security laws says the extraordinary powers used to detain people without charge following counterterrorism raids in Sydney are "worse than useless" and should not be used.

The Australian Federal Police revealed on Friday they had used for the first time Howard government-era "preventative detention orders" to hold three men without charge for 36 hours after raids across western and north-western Sydney on Thursday. The men were released on Friday.

Sydney barrister Bret Walker, SC, the former independent national security legislation monitor, said the laws were "much more trouble than they are worth", in part because it was "unlawful" to question a person who was held under such an order.

"They are worse than useless, because you can't question a person while they are being preventatively detained under a PDO," Mr Walker said.

The orders were issued by the NSW Supreme Court under powers introduced after the 2005 London bombings. The court had to be satisfied "there are reasonable grounds to suspect" a person "will engage in a terrorist act" or was involved in the planning or preparation for such an attack.

The terrorist attack should be "imminent", meaning it was "expected to occur in the next 14 days".

Mr Walker said there was already a power under Commonwealth law for a person suspected of terrorism to be detained for questioning before charge for 24 hours, which could be spread over a maximum of eight days.

"Why we would ever move away from the tried-and-tested method of arrest ... during which you can question, and at the end of which you can charge," Mr Walker said.

The Abbott government had indicated its intention to abolish the office of the independent security legislation monitor but reversed its position earlier this year. The position was vacant as Mr Walker's three-year term had expired.

Mr Walker said "none of us will be able to understand [the AFP's rationale for using the orders] unless and until my successor reports upon this episode".

"We're left guessing but we can infer some things from the fact these people were released," he said. "That means that the authorities didn't think the situation justified seeking them to be detained longer ... or the issuing authority, that is, probably a judge, was not persuaded that there was sufficient justification."

In a report in December 2011, Mr Walker said that "accidental and other criminal modes of people being killed far outnumber what has happened by terrorism".

"Should we, as a society, give consideration to ... preventative detention orders against violent husbands, drunken or adolescent drivers or careless foremen? Surely not. Have we properly articulated the reasons why counterterrorism should produce an opposite response?"

The powers to issue PDOs were due to expire next year because of a sunset clause written into the legislation. But under a raft of counterterrorism laws the Abbott government planned to introduce to Parliament this week, the powers would stay for another 10 years.

George Williams, an expert in anti-terrorism laws at the University of NSW, said it was "widely assumed" PDOs would be abolished.

He said there was no provision for PDOs in comparable jurisdictions such as the UK and the US.

"Countries with a significantly greater terrorist threat don't have this power and aren't considering it," Dr Williams said.

"Giving the ability to lock people up – all you can say is 'I'm safe, but can't be contacted for the time being' – doesn't really seem consistent with the democracy we think we live in."

Ben Saul, a professor of international law at the University of Sydney, said another concern was the "creeping expansion" of laws allowing people to be detained without the same safeguards or scrutiny as people held following arrest and charge.

"Fourteen days for terrorism is one thing but obviously indefinite detention of refugees on security grounds is even worse," Dr Saul said.

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