Civil liberties lawyers say proposed changes to anti-terrorism laws go well beyond what is needed.
Prime Minister Tony Abbott on Tuesday announced enhanced powers for intelligence agencies and police to deal with terrorism, including the threat of Australians returning home from training or fighting in conflict hotspots such as Iraq and Syria.
"The measures represent an attempt to use the current problems of Australians fighting with terrorist groups as a power grab for extra powers, the need for which is not currently made out," Australian Council for Civil Liberties president Terry O'Gorman told AAP.
In contrast, counter-terrorism laws enacted after the September 11 attacks in the United States were approached in a measured way.
Broadening the listing criteria for terrorist organisations to "promotion and encouragement of terrorism" would run the risk of "chilling" or criminalising public debate about the activities of such organisations.
The federal government hadn't made the case for lowering the threshold for arrest without warrant.
"Already the threshold for arrest is relatively low and the need to further weaken the standard of evidence has not been made out," Mr O'Gorman said.
While there may be a case to improve the Australian Federal Police's ability to seek control orders on returning foreign fighters, such orders had rarely been used.
"Improving the ability to seek these means lowering the evidence threshold and there is going to have to be a strong case made out for that," he said.
The veteran defence lawyer said lowering the standard of proof for elements of offences committed overseas would make it harder to defend clients in court.
"You are severely compromised in doing your job because of the fact you can't go overseas and conduct investigations to assess the credibility or any faults, including fabrication, of that evidence," he said.
"Certainly there are police actors in many overseas countries who you wouldn't trust to help you cross the road."
