A Supreme Court judge has permanently stayed the prosecution of two people charged with a toddler's death, saying nothing could be done to bring about a fair trial.

Tania Walker and Daniel Simmons were each charged with child homicide last March, in relation to the 2008 death of Ms Walker's 23-month-old daughter, Angela Bannister.

A trial was originally set down for this year, following a committal hearing in Bendigo last year.

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But Justice Paul Coghlan determined the matter should not proceed and discharged Ms Walker and Mr Simmons.

Justice Coghlan found the destruction of material obtained from telephone intercepts and surveillance devices put each of the accused at a significant disadvantage, as what they said formed an important part of the case against them.

He said this occurred in a period of unexplained delay, but apart from the evidence of a medical expert, the case was almost exactly the same as it was at the end of an inquest held in 2011.

He determined that "there are real questions about causation and a particular unfairness to the accused who is not the perpetrator of the injuries".

"The way the prosecution case is now put that each accused is not that perpetrator," Justice Coghlan said.

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In July 2018, the Office of Public Prosecutions recommended that police undertake further investigation to determine whether Ms Walker or Mr Simmons could be charged with child homicide on the basis of gross negligence.

But Justice Coghlan said this was inappropriate of the Office of Public Prosecutions, as it did so based partly on inadmissible evidence from the coronial inquest.

Even if this material were not "caught by the strict terms" of the legislation regarding such evidence, he said, "it nonetheless should not have been used as a basis for relaunching a case which was more than 10 years old".

Justice Coghlan also found that while it would be in the public interest to have a trial, he was not satisfied the means of identifying criminal responsibility was appropriate.

The Office of Public Prosecutions has notified Justice Coghlan that it will not seek an interlocutory appeal against the ruling.

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The prosecution had alleged Ms Walker and Mr Simmons were guilty of child homicide because they had failed to seek timely medical attention for the little girl, and this caused her death.

Angela died on July 19, 2008 from internal bleeding caused by injuries to her chest.

She suffered numerous injuries, including broken ribs, a broken pelvis, and bruising.

Neither Ms Walker nor Mr Simmons have ever been charged with inflicting the fatal injuries.

They both pleaded not guilty to child homicide following a committal hearing in Bendigo last November.

Angela was one month shy of her second birthday when she died.

Earlier

The mother of late Echuca toddler Angela Bannister and the woman's partner will not face trial over the little girl's death.

Tania Walker and Daniel Simmons were each charged with child homicide last year in relation to the July 2008 death of 23-month-old Angela.

On Wednesday, Supreme Court judge Justice Paul Coghlan ordered Ms Walker and Mr Simmons be discharged.

Justice Coghlan first made an order on August 19 that the indictment against the couple be permanently stayed and they be discharged, but a stay on the order was put in place until Wednesday.

Ms Walker and Mr Simmons were originally scheduled to stand trial over Angela's death this year.

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