This is one of Queensland's most secretive rooms and has played host to murderers, organised criminals and corrupt officials.

Some who are brought into the Crime and Corruption Commission (CCC) coercive hearing rooms do not know exactly why they have been summoned, but will be urged to sit and answer questions.

Anybody refusing to cooperate can be jailed. Anyone caught lying can expect to spend a minimum of six months behind bars.

By telling the truth, someone else could be locked up.

The hearing rooms resemble a mini court, but there is no public gallery or room for supporters — just space for the witness, lawyers, a presiding officer and CCC staff.

CCC chairman Alan Macsporran says organisation doesn't use its powers lightly. ( ABC News: Kristian Silva )

Questioning can take hours or sometimes even days. When it is all over, witnesses leave and are sworn to secrecy, risking charges if they dare tell anyone about what transpired.

Unlike traditional police interviews, the basic legal right to silence does not exist in the so-called "star chamber".

The nickname, used by lawyers and the media, dates back to a notorious, ancient English court which stifled witness rights and was used by the monarchy to suppress dissenters.

While witnesses' testimony cannot be used against them, the CCC can still use damning evidence if they find someone else willing to point the finger.

Pressure to 'say what the commissioner wants to hear'

The coercive hearings were established in the aftermath of Queensland's groundbreaking Fitzgerald Inquiry and were designed to crack open major cases when police struck investigative roadblocks.

But some civil libertarians, including veteran lawyer Terry O'Gorman, argue the CCC's extraordinary powers are used excessively.

"In other countries where the right to silence doesn't exist, [witnesses] are forced to answer questions and often they provide false confessions because of the pressure they're under," Mr O'Gorman said.

Terry O'Gorman wants the CCC's powers to be curbed. ( ABC News: Kristian Silva )

In a separate case, a high-profile Queensland criminal lawyer wrote about one of his clients who faced a star chamber hearing to give evidence about his "political figure" boss.

In a magazine article published this year, the lawyer said his client knew nothing of the alleged wrongdoing by his superior, but the client feared he would be accused of lying to the CCC if he said that.

"There were a lot of hard questions, but one easy answer: say what the commissioner wanted to hear," the lawyer wrote.

"My client agreed that he'd seen it and heard it. He signed up the statement and they let him go home."

Investigative hearings quadruple in 10 years

In 2006-2007, the CCC (formerly the Crime and Misconduct Commission) held 81 days of investigative hearings.

A decade on, that number reached 342 and the CCC expects to hit a similar figure by the end of 2017-18.

Mr O'Gorman wants the CCC's powers curbed so it can only summon witnesses to the star chamber with the permission of a Supreme Court judge.

A coercive 'star chamber' hearing room at the CCC's Brisbane headquarters. ( ABC News: Kristian Silva )

He said it was wrong for the powers to be used to haul low-level criminals and whistleblowers into coercive hearings.

"Some of them get down to a level where a hearing should never have been conducted," Mr O'Gorman said

"As someone who's been involved in civil liberties for over 40 years now, that balance is seriously skewed against civil liberties and in favour of police powers and CCC powers."

Criminal lawyer and Queensland Law Society deputy president Bill Potts said facing a coercive hearing was a daunting experience for many people.

"There is only one piece of advice that can be given to people in these circumstances — and that is to tell the truth," he said.

'YouTube celebrity' forced into secretive hearing

Recently, a self-described Brisbane "YouTube celebrity" was called to the star chamber because investigators wanted to find out who was behind the leak of a top-secret report about Queensland Rail network problems.

Paul Pluta was charged with disclosing details about a CCC investigation. ( Supplied: YouTube )

Acting as a middleman, Paul Pluta received the report from his source, passed it on to journalists and posted several videos on his own channel, causing major embarrassment for QR and the State Government.

Mr Pluta was later charged with breaching the CCC Act for allegedly informing a third party that he was due to face the star chamber.

When contacted for comment for this story, Mr Pluta declined to be interviewed, saying his case was still before the courts.

Mr O'Gorman said the Pluta case was an example of coercive hearings being used for trivial matters, and said Queensland whistleblowers had to think "long and hard" about coming forward.

"It'd be different if you were talking about a terrorist incident, but this was talking about problems about Queensland Rail that needed, in the public interest, to be disclosed," Mr O'Gorman said.

Whistleblowers 'should see us first': CCC chair

CCC chairman Alan Macsporran disagrees with critics who say the star chamber system deters whistleblowers.

"People who have access to confidential information are under an obligation of trust not to disclose that without very good reason," Mr Macsporran said.

"If there's, for instance, a belief that they want to blow the whistle, they should come to us confidentially to report the matter and have us investigate.

"If at the end of the day we decide not to take any action and they think that's the wrong result — that we've dropped the ball or we haven't investigated properly — they can then go to the media."

Mr Macsporran said the ultimate test of whether the CCC's powers were being used appropriately was whether judges and magistrates allowed its evidence to be used in court despite challenges from defence lawyers.

He said the CCC also had to report several times a year to a bipartisan parliamentary oversight committee.

"We as an organisation take extremely seriously the extent of those powers and we only exercise them when they're required," he said.

Watchdog helps solve Palmer, McCulkin cases

Barbara McCulkin (right) and her daughters Vicki (left) and Leanne (centre) were murdered in 1974. ( Supplied: Queensland Police Service )

Mr Macsporran pointed to recent successes, including evidence secured by the CCC that helped prosecutors jail two men over the McCulkin murders, a triple homicide cold case that was unsolved for more than 40 years.

"[The coercive hearings] were totally instrumental in breaking open that cold case," he said.

Mr Macsporran said the CCC also played a critical role in finding out what happened to murdered schoolgirl Tiahleigh Palmer.

For months, Tiahleigh's foster family the Thorburns stuck to the story that she was dropped at school before she was killed, although police suspected they were lying.

Three members of the Thorburn family perjured themselves before the CCC, but later came clean and flipped on Tiahleigh's foster father, Rick Thorburn, who pleaded guilty to her murder last month.

Rick Thorburn (right) pleaded guilty to Tiahleigh Palmer's murder after his family agreed to testify against him. ( Supplied: Queensland Police Service and AAP )

"Once they realised they had been caught out and were facing those [perjury] charges, it was very much in their interest to cooperate, to lessen the impact of the sentencing on those charges," Mr Macsporran said.

"Although they went to prison, they went for a shorter term than what would otherwise have been appropriate."

CCC investigations have also helped authorities investigate child abuse cases, criminal bikie gangs and misconduct within the Queensland Police Service.

In the past two years, public hearings — which are streamed live online — have been held into corruption in the state's local government and the prison system.

Mr Macsporran said the commission's staff of 335 were kept constantly busy. In the eight months to March, they assessed more than 2,000 complaints.

"For the matters we're dealing with currently and look like doing in the future, I'm satisfied the powers we have are adequate," he said.