The powers of Australia's domestic spy agency, ASIO, are rotten at their core, could be used against innocent Australians by an unscrupulous government and should be repealed, the law professor George Williams has warned.

Launching a campaign to wind back the ''excessive and disproportionate powers'' given to ASIO since the September 11, 2001, terrorist attacks, Professor Williams said that collectively the laws ''represent the greatest assault on civil liberties in Australia since World War II''.

Professor Williams, the Anthony Mason professor of law at the University of NSW, was speaking at the NSW Council for Civil Liberties dinner in Sydney where a national campaign to roll back the nation's anti-terrorism laws was unveiled.

The anti-terrorism laws have sunset clauses which come into effect in 2016. At that time they can be repealed, amended or made permanent.

The national campaign aims to force decisions of intelligence agencies, which negatively affect human rights, to be subject to a merit review and to ensure any future laws are scrutinised by the community before they are enacted to stop further erosions of civil liberties.

The council launched the campaign on the back of the public outcry about asylum seekers who had been assessed as refugees but who had adverse ASIO assessments resulting in them being held in detention indefinitely.

The campaign comes as the director-general of ASIO, David Irvine, launches a publicity campaign of his own with a rare interview to defend ASIO's proposal to extend its powers under national security laws to search phone and internet data and to allow ASIO officers to commit crimes without being charged.

Mr Irvine has told the ABC's Background Briefing that ASIO is being left behind because of advances in technologies. He also said that it had experienced intelligence failures because of changing technology.

''Today there are hundreds of different ways of communicating electronically and the law does not cater for those ways in the way it should,'' Mr Irvine told the ABC.

However, Professor Williams said there had been a frenzy of lawmaking in the past decade with 54 pieces of anti-terrorism legislation introduced - 48 of them under the Howard government - making an average of one new law every seven weeks.

He said there was no need for any new powers.

''The powers are more consistent with the apparatus of a police state, such as General Pinochet's Chile, than the laws of a modern democracy,'' he said.

''They have no place in Australia, should be repealed.''

ASIO Seen As Serious Threat To Innocent Citizens