Judge Richard Posner, a supposedly liberal-leaning jurist regarded by many as a future US Supreme Court candidate, said traditional concepts of criminal justice were inadequate to deal with the terrorist threat and the US had "over-invested" in them.

His proposed "big brother" solutions flabbergasted delegates at the Australian Bar Association's biennial conference, where David Hicks's lawyer, Major Michael Mori, is to be awarded honorary life membership.

"We have to fight terrorism with our strengths, and our strengths evolve around technology, including the technology of surveillance," said Justice Posner, a prolific legal scholar who sits on the US Court of Appeals for the Seventh Circuit.

"Are there terrorist plots that are at a formative stage among the large US Muslim community of two to three million people? In the 600,000 Canadian Muslim population, are there people planning attacks on the US?

"What we have to do is discover the extent of the terrorist threat to the US. There is a danger, and it demands a rethinking of some of our conventional views on the limits of national security measures.

"We should think of surveillance as preventative, not punitive. We should think of controls that have nothing to do with warrants or traditional criminal justice to prevent abuses."

Judge Posner said the US temper and culture could not sustain repeated terrorist attacks.

Melbourne QC Tim Tobin said it was a shock to hear such hard and isolationist positions coming from a judge known as a liberal thinker. While he was disturbed by the judge's proposed crackdown on US and Canadian Muslims, he suspected the sentiment would be welcomed by the Howard Government.

Judge Posner raised the prospect of secret trials as a "tailored regime" to prosecute terrorists in cases where there was a concern about classified information going public.

Queensland SC Glenn Martin said he had been "jolted" by the address: "I hope we never have secret trials in Australia."

Judge Posner said the US was "a law-saturated society where even non-lawyers tend to think ofproblems in terms of legal categories".

"Criminal justice and war are the two responses we have to terrorism. Each comes with its own legal institutions and doctrines and regimes but the struggle against international terrorism doesn't fit either very well."

He said it was "quite misplaced" to suggest national security measures in force or contemplated in the US could endanger liberty and undermine the political system. This was because governments could no longer conceal what they did: "We have a very aggressive media and a huge and complex government where many people in the government are quite willing to talk to the press."