About 500 people have marched through the Adelaide CBD rallying against proposed changes to the state's protest laws.
The state government proposed changes to laws that would strengthen penalties for obstructing public places in response to Extinction Rebellion protests last week.
A climate change protester was charged with obstructing a public place after she abseiled down Morphett Street bridge with a rope and was suspended over North Terrace, causing traffic delays.
Another four protesters were charged with offences, including property damage, after allegedly throwing paint at the Santos building.
The proposed changes to the Summary Offences Act — backed by the state opposition — would mean anyone who "intentionally or recklessly engages in conduct that obstructs the free passage of a public place" would face possible three months jail or a $50,000 fine.
Currently, there is no option for jail time and the maximum fine is $750.
The government is hoping the amendments to the law will pass the Legislative Council next week.
But Greens MLC Robert Simms said his party will be voting against the bill because "it is so deeply flawed".
"The government should be sending this bill to the bin, not the Upper House, but if they are going to proceed with it then we will try to make some amendments," he said.
"One of the amendments that I'm moving will be to add in a sunset clause to this bill so that it expires in 12 months time.
"We are also adding in a clause requiring a review after a 12-month period and I'll also be introducing a reasonableness test so that people who are caught under this bill will have a possible defence."
About 80 community groups, including Amnesty International Australia, have signed a letter calling on the government to withdraw the bill.
The organisations listed their support in a full-page advertisement taken out in Friday's edition of The Advertiser titled Protect Our Right to Protest — Before It's Too Late, which was authorised by the South Australian Council of Social Service.
'Almost wartime measure'
The Law Society of South Australia and the South Australian Bar Association have also jointly written a strongly worded letter to the Attorney-General outlining a long list of concerns about the proposed new laws.
"Passing law without consultation with relevant stakeholders at such a rapid pace is a practice that should be condemned in the strongest terms," the letter states.
The letter states that the speed at which the bill is being rushed through parliament "seriously undermines the democratic process" as well as the ability of the parliament (and by extension the general public) to receive considered and appropriate advice on proposed new laws.
The Law Society's president James Marsh told the ABC the rush to get the significant legal changes passed is "deeply troubling".
"They haven't given a reason for acting so speedily, there does not seem to be an immediate pressing threat to the peace and good order of South Australia that warrants this kind of almost wartime measure," he said.
The legal bodies raised concerns about the legal wording of the proposed reforms which would significantly shift the onus of proof for the offence of obstructing a public place.
"The effect is that a person only has to turn their mind to the possibility that an obstruction will occur, even though the consequence is entirely unintended, to be found guilty of the offence," the letter states.
"The scope of the offence is not limited to protest activity and could apply in many contexts."
Shadow Attorney-General Josh Teague said the bill was "a public policy response to a public insult".
"I look forward to seeing its passage through the parliament," he said.
Education Minister Blair Boyer said he believes "there is room to move within the legislation" to protect people's right to protest but also the avoid such public disruptions.
"I think the way that Peter Malinauskas has operated in his first year and a bit as the premier of South Australia has shown that he's willing to work with the crossbench and other members of parliament to get good outcomes for South Australia and I'm confident that's what we can do," he said.
