Under new laws that have passed parliament, coroners have greater power to compel witnesses to give self-incriminating evidence at inquests.

It's hoped the laws could resolve historic cases including whether some people have so far escaped justice over the 1973 firebombing that killed 15 people.

Previously coroners could only force witnesses to give potentially self-incriminating evidence relating to deaths from 2003 onwards.

That time limit has now been lifted, paving the way for a re-examination of historic crimes.

"For deaths prior to 2003, witnesses could refuse to give self-incriminating evidence, which made it harder for coroners to find out what actually happened," Acting Attorney-General Stirling Hinchliffe said.

"This led to the creation of a hard core of remaining cases that have not received the benefit of the modern coronial regime and remain unresolved to this day."

But there's a catch.

Self-incriminating evidence extracted from unwilling witnesses can't be used in criminal proceedings unless perjury is involved.

The government ordered a fresh inquest into the Whiskey Au Go Go bombing in June 2017, saying witnesses who'd previously refused to speak might now be willing to do so.

James Finch and John Andrew Stuart were convicted over the attack, but both men insisted they were stitched up.

At one stage Stuart, who died in prison in 1979, climbed up on the roof of Brisbane's Boggo Road jail, pulled out dozens of bricks and then used them to spell out the message: Innocent - victim of police verbal.

Mr Finch served 15 years behind bars before he was deported to the UK in 1988.

In 2018, he said he was willing to take a lie-detector test to show his confession to police never happened.

At the time, then Queensland Police Commissioner Ian Stewart said he was sure the coroner hearing the new inquest would be interested in anything Mr Finch had to say.

The new inquest was ordered one day after hardened criminals Vincent O'Dempsey and Garry Dubois were handed life sentences for murdering Brisbane mother Barbara McCulkin and her two daughters in 1974.

O'Dempsey's trial heard he may have been motivated to kill Mrs McCulkin over fears she would try to implicate him in the Whiskey Au Go Go bombing.

O'Dempsey has denied being involved.

Australian Associated Press