Queensland Law Society president Bill Potts says Australia’s highest court’s decision to allow an appeal against Baden-Clay’s downgraded manslaughter conviction will have consequences for how the law views intent in murder cases. In what has been one of the country’s highest-profile cases this century, the former Brisbane real estate agent, 45, was two years ago convicted by a Supreme Court jury of murdering his wife Allison.

Her body was found underneath Kholo Creek Bridge 10 days after he reported her missing in April 2012.

But late last year the Queensland Court of Appeal changed his conviction to manslaughter after ruling that it could not be proved beyond reasonable doubt that Baden-Clay intended to kill the mother-of-three.

In what has been described as an extremely rare decision, the High Court on Thursday granted the Queensland Director of Public Prosecutions special leave to contest the ruling.

The High Court deals with approximately 4000 applications for special leave each year and it is only granted in less than eight per cent of cases.

A full bench of the High Court will hear oral submissions from both sides on a date yet to be set, but expected within the next three months.

Mr Potts said the court’s ultimate ruling would have ramifications for murder cases across Australia.

“In this case, they’ve found that there is a sufficient difference between the way in which the law has been interpreted between the states for this matter to go to a full hearing,” he told AAP.

“It’s not just a matter of whether it ought to be murder or manslaughter, but they’re really looking at the legal principles of how intent can be determined in a murder case – and what evidence can be utilised to demonstrate that intent.”

After oral submissions are heard, the court could rule one of three ways: to confirm the decision of the Court of Appeal and send the matter back there for sentence; to confirm the original verdict of murder; or to remit the matter back for trial, which Mr Potts said was unlikely.

Decisions are reserved for two to three months.

Allison’s cousin, Jodie Dann, was in the High Court in Canberra and wept after the decision was announced.

Her parents, Priscilla and Geoffrey Dickie, were not present but released a short statement saying they would not be commenting.

Both the DPP and Baden-Clay’s lawyer, Peter Shields, declined to comment.

During Baden-Clay’s trial, jurors heard details of his extra-marital affair with a colleague, efforts to repair his marriage and significant financial troubles.

Pivotal to the prosecution’s case were marks on his cheek which experts testified were consistent with fingernail scratches, but Baden-Clay insisted he cut himself with a blunt shaving razor.

During the Court of Appeal hearing, his lawyers argued Baden-Clay may not have intended to kill his wife during a violent argument and disposed of her body in a panic to avoid the repercussions.