Pro-Palestine protesters marching on the Sydney Opera House will be met with the full force of the law after the state's top court barred a planned demonstration due to crowd-crush fears.
The Court of Appeal verdict on Thursday will allow officers to move on or arrest those gathering on the iconic building's forecourt after NSW Police challenged the Palestine Action Group's proposed rally.
Organisers have pivoted and agreed on another route with police for the Sunday event after estimating about 40,000 people could have joined the march through Sydney's city centre to the steps of the waterside landmark.
In a pointed message to protesters, Assistant Commissioner Peter McKenna said police would be out in force to enforce the court's prohibition order.
"There will be a large police presence ... it won't just be a free-for-all," he told reporters.
"Anyone who thinks that they could go to the Opera House still and be a part of any type of demonstration or public assembly, you will be committing an offence and appropriate action will be taken by us."
When asked how police would screen people for anyone failing to comply with the court order, Mr McKenna said he would not delve into operational matters.
Justice Stephen Free said a protest of the size forecast by the activist group would have "given rise to a risk of crowd crush".
The appeal court judges pointed to the "exceptional risks associated with the particular route and ultimate destination of the procession" combined with the crowd size and its movements.
That informed the court's conclusion about "the unacceptable nature of those risks".
Entry points to the forecourt and requirements for security checks would have pushed protesters into a tight space that could lead to crowd crush, the three judges found.
Chief Justice Andrew Bell raised concerns over public safety during Wednesday's hearing, pointing to the 1989 Hillsborough crowd crush disaster and evidence the Opera House forecourt could only safely accommodate 6000 people.
"The court proceedings did not go our way today and we won't be marching to the Opera House," Palestine Action Group organiser Damian Ridgwell said after the decision.
"But we know courts often get things wrong."
He said Sunday's demonstration would instead head down George Street in Sydney's city centre in co-operation with police.
"Our right to protest is paramount in a democratic society," Mr Ridgwell said.
Nick Hanna, a lawyer for the organisers, characterised the legal showdown as a "David vs Goliath battle" after the Opera House Trust, Botanic Gardens management and Jewish groups all gave evidence supporting the court challenge.
He warned anyone thumbing their nose at the decision and rallying at the Opera House forecourt on Sunday could be considered in contempt of court.
Premier Chris Minns welcomed the court for making the right decision but tersely declined the activist group's demand to light up the landmark's sails with the colours of the Palestinian flag.
A controversial, snap rally was held on the Opera House steps days after Hamas's deadly October 7, 2023 attack on Israel following a NSW government decision to light the sails in the colours of the Israeli flag.
"The right to engage in public protest is fundamental but not unlimited ... our community feels relieved and vindicated by this decision," the Executive Council of Australian Jewry and the NSW Jewish Board of Deputies said in a joint statement.
Organisers pointed to previous non-ticketed events at the Opera House, like popular light show Vivid, that were managed safely.
They also mentioned a concert by Crowded House on the steps of the Opera House to a crowd of 100,000 people in the 1990s as tangible examples.
But Mr McKenna contested the figures and argued they were ticketed events that required months of planning.
