The case of two Queensland women mysteriously shot dead in 1991 has returned to the courtroom with a new push to prosecute the husband of one victim.

The unsolved case of two Queensland women shot dead more than 20 years ago is back in court after a fresh bid to bring the main suspect to trial.

However, Queensland’s attorney-general, who is behind the push, faces a tough task to convince the state’s Court of Appeal to overturn a previous decision.

Alan Leahy was committed last year to stand trial over the shooting murders of his wife and her friend in far north Queensland in 1991.

The order by then-coroner Michael Barnes was successfully appealed by Mr Leahy in the Supreme Court but Attorney-General Jarrod Bleijie is now challenging that decision in the Court of Appeal.

His lawyers argued in court on Wednesday that Supreme Court Justice James Henry’s ruling last August was an interference in the criminal process.

“There’s been an interference with the coroner’s decision,” Peter Davis QC said.

“The coroner’s decision, well publicised, was that this gentleman should be committed to trial for murder.”

Mr Leahy’s barrister Peter Callaghan SC argued the attorney-general failed to demonstrate an error in Justice Henry’s reasoning.

Justice Henry found Mr Barnes erred by relying on lies Mr Leahy allegedly told in relation to the case as evidence of his guilt.

The attorney-general is also seeking to overturn a ruling that the state pay Mr Leahy’s legal costs.

Mr Bleijie must also persuade the court to grant an extension of time to appeal, after filing the documents about a month late.

The three Court of Appeal judges reserved their decision and granted Mr Davis more time to file written submissions to support his case.

The bodies of Julie-Anne Leahy and Vicki Arnold were found in a four-wheel drive in remote bushland in the Atherton Tablelands near Cairns on August 9, 1991.

Following two inquests, the deaths were deemed to be a murder-suicide until a third inquest led Mr Barnes to find otherwise and commit Mr Leahy to stand trial for murder.

Even if the attorney-general’s appeal fails, the Director of Public Prosecutions can still pursue an indictment against Mr Leahy.

Mr Davis acknowledged the appeal could be seen as pointless but said it didn’t mean the committal order shouldn’t be defended.