Brisbane's Magistrates Court will operate 24 hours a day during the G20 week, with the judiciary preparing for the possibility of thousands of arrests, the state's Chief Magistrate says.

In a Queensland first, after-hour hearings in the court will also be live streamed to the internet for everyone to see during the week of the leader's forum.

Chief Magistrate Ray Rinaudo today revealed the final plan for G20, set to start in 10 days.

He said the judiciary had spent months preparing to deal with the possibility of thousands of arrests.

"It was an issue of planning for the worst and hoping for the best," Mr Rinaudo said.

The Magistrates Court will operate all hours, from November 10 to 16.

A video-link will be set up so defendants will have a quick hearing before a magistrate without having to leave their holding cell.

Courts will be heavily guarded during after-hours and closed to the public but hearings during those hours will be broadcast publically on the internet.

Anyone charged with a G20 offence will be held in the cells under the Queen Elizabeth II Courts of Law complex, which can hold up to 150 people.

All other criminal matters will be sent to the Roma Street Magistrates Court.

Mr Rinaudo said the new measures were designed to work more transparently and expeditiously.

'We've planned for the worst but hope for the best'

Authorities have to plan for the possibility of thousands of arrests, similar to Toronto in 2010 when it hosted the G20.

"The Canadian experience was that there was substantial arrests, it was a very big volume," Mr Rinaudo said.

"We use that as being the model about how we would do our work to be able to handle that if that's what would happen here.

"I'm hoping that would not happen here but we've planned for the worst."

From Saturday, the G20 legislation is being enforced at the core restriction zone in and around the Brisbane Convention and Exhibition Centre, and will be slowly rolled out across other sites and suburbs over the next fortnight.

There are similarities between the G20 legislation and Queensland's anti-bikie laws where defendants need to prove their innocence.

Queensland Law Society president Ian Brown said the legal industry was well prepared.

"There will be a number of private lawyers who will be available on-call to assist people who might be arrested related to G20," he said.

"That's in addition to the assistance being provided to Legal Aid Queensland."

Mr Brown said it was important for members of the public to be aware of what restrictions come into effect in the declared zones.

"The interaction that they may have with members of the police service and security forces will be different," he said.

"They may be asked to explain why they have certain goods in their possession; they may be asked to undergo basic searches while they go about and do their daily business.

"Provided people act appropriately and in accordance with directions that they are given, then that will keep disturbances to a minimum."

RAAF sets up radar sites to watch Queensland skies

The Royal Australian Air Force (RAAF) said mobile radar sites around south-east Queensland during the G20 summit would ensure there were no surprise aerial attacks.

The high-tech three-dimensional defence radars could detect any aircraft from 350 kilometres away.

A RAAF group captain who could not be named for security reasons said the aerial defence system would detect any suspicious activity in the skies.

"There is an existing number of air traffic control radars both military and civilian in the Brisbane area but we thought it prudent to add additional defence radar to provide a little bit of extra coverage," he said.

"It's just there to provide a dedicated surveillance function and its data is actually fed back to our main operations centre at Williamtown [north of Newcastle] which is where we will be manning our operations from.

"It will detect aircraft of a reasonable size out to about 350 kilometres and up to about 100,000 feet which is pretty much beyond most conventional aircraft."