Queensland's double jeopardy provisions are being used for the first time after a man was charged in relation to a murder in the 1980s.

The man was arrested today, triggering a "legal mechanism" whereby an application will be made to the court for an acquitted person to be retried for the offence.

Police will now have to appeal to the Supreme Court to allow a re-trial.

Because of legal restrictions preventing the identity of the person subject of the application to be publicised, police would not reveal any further details, except to say he had already faced court once over the alleged murder and been acquitted.

This is the first time double jeopardy provisions have been exercised in Queensland.

Legal expert Bill Potts, who has 36 years' experience in criminal law, said it was an "extraordinarily unusual" step.

"The general principle in law is that people cannot be tried twice for the same offence and there is a sensible reason for it," Mr Potts said.

"Otherwise we would be seeing people retried over and over again."

He said the Queensland Government introduced double jeopardy legislation in 2014.

"Under this law if a person is charged with a serious criminal offence — which includes murder — and is acquitted by a jury, in effect a person can be charged a second time if new evidence emerges which was not available to the DPP at the time of the original trial," he said.

"That may include medical evidence, it may include eye witnesses coming forward, it may include new confessions."

According to the Criminal Code Act, a retrial may be ordered for two reasons: if there is "fresh and compelling evidence" or if the acquittal was allegedly tainted.

It is not known which provision was activated in this case.

When will we know more about the case?

Mr Potts said investigations of this kind were extraordinarily sensitive, which was the reason why few details were available to the public.

"It often involves 'assets' such as informants and the like and they are very concerned that the evidence remains clean and untainted," he said.

"So while it is an unusual step, once a person is charged it is important that the public understands the process is being done not to abrogate their rights but to see justice done."

Mr Potts said once a person was charged and brought before a court, then there were — in Queensland — almost no restrictions for what could be published.

"Courts do have a power in certain circumstances to suppress evidence or supress names of witnesses, but in Queensland thankfully that is a very rare step," he said.

What sparked changes to double jeopardy laws?

Many years ago, there was a case where a baby was abducted, brutalised, bitten and then thrown onto the top of a toilet block in Ipswich.

Seventeen-month-old Deidre Kennedy's body was found just 500 metres from the family home.

Deidre Kelly was abducted, brutalised and thrown onto the top of a toilet block in Ipswich. ( Supplied )

Former RAAF recruit, Raymond Carroll was convicted of the baby's murder in 1985 but it was overturned on appeal.

In 2000, a jury sent him to jail for lying about the murder but his perjury conviction was turned over by the High Court of Australia.

In 2014, the then attorney-general Jarrod Bleijie said the 800-year-old law was a roadblock to justice, but the change would "stop offenders from potentially and literally getting away with murder".

While double jeopardy laws changed in 2007 across most of Australia to allow acquitted people to be retried if new evidence came to light, Queensland could only target people committing crimes after 2007.

Mr Bleijie's legislation made the changes entirely retrospective, allowing persons to be tried for the same crime, regardless of when they were acquitted.