Legal challenge to CBD-wide warrantless searches

Powers to stop and search people without a reason across a vast swathe of Australia's second largest city will be legally challenged as police insist they're on "solid ground".

Protest organiser Tarneen Onus Browne and performance artist Benny Zable have filed a legal and constitutional challenge against Victoria Police's decision to declare Melbourne's CBD and surrounds a "designated area" for six months from November 30.

The declaration empowers officers to search a person or vehicle without a warrant, including asking someone to remove outer clothing or take items out of their pockets.

Police can also carry out searches through an electronic wand or pat down.

The pair, represented by the Human Rights Law Centre, claim the legal threshold for the six-month designation across the area was not met and the decision breached Victoria's Charter of Human Rights and Responsibilities.

They also argue police powers to order the removal of face coverings at protests interfered with rights to peaceful assembly, freedom from arbitrary arrest and detention, non-discrimination, privacy and freedom of expression.

The Federal Court challenge seeks to have the designation ruled invalid and orders to remove face coverings found unconstitutional.

"This is absolutely about holding police accountable for making these sorts of extraordinary decisions and orders," Human Rights Law Centre legal director Sarah Schwartz told reporters on Monday.

Victoria's Control of Weapons Act previously limited a designated area declaration to 12 hours but the laws changed in March to lift the threshold to up to six months.

Mr Zable, who has protested for more than 45 years in his 'Greedozer' costume, said he had been told to remove his mask in designated areas and was worried the expanded powers would lead to more violence.

His fellow plaintiff, a January 26 Invasion Day protest organiser for the past 10 years, said the powers would "supercharge the harassment and targeting" of Indigenous people.

"The Allan government and Victoria Police cannot create a zone in the middle of Melbourne where human rights are an option," the Gunditjmara, Yorta Yorta, Bindal and Meriam person said.

The centre wants the matter heard before January 26 so the day of national protest can continue without "undue police interference".

Deputy Commissioner Bob Hill said he believed Victoria Police was on "solid ground".

"We do not discriminate," he said.

"It's a random selection of people and we do not have any tolerance for racial profiling in our organisation."

Deputy Premier Ben Carroll said the government made "no bones" about giving police every power and resource to keep the community safe and denied the threat of searches would scare people away.

Victoria Police has used the expanded powers to declare four Melbourne shopping centres designated areas as part of a 90-day operation over the festive period.