The court's ruling today means that Cardinal Pell will be released from Barwon prison today (April 7).

The decision was unanimous

Pell, 78, was found guilty by a jury of the rape of a 13-year-old choirboy and sexual assault of another at St Patrick's Cathedral in Melbourne in 1996 but Australia's most senior Catholic has always denied any wrongdoing.

The Victorian Court of Appeal in August upheld a jury verdict convicting Pell in a 2-1 ruling.

In a 12-page application for special leave to the High Court, Pell's lawyers argued Chief Justice Anne Ferguson and Court of Appeal president Chris Maxwell made two errors in dismissing the earlier appeal.

Bret Walker SC and Ruth Shann say a mistake occurred because Pell was required to prove the offending was impossible, rather than leaving that onus to prosecutors.

Secondly, they argued the judges erred in not finding the jury's verdicts unreasonable, claiming there was reasonable doubt about whether opportunity existed for the crimes to have occurred.

They also claimed that changes in law over the decades since the crimes were said to have occurred make it more difficult to test sex assault allegations.

They argued Pell should be acquitted of all charges for a number of reasons including inconsistencies in the complainant's version of events.

But prosecutors argued there is no basis for the appeal, and the Victorian courts did not make an error.

Pell is serving a six-year jail term and won't be eligible for parole until he has served three years and eight months of his sentence.

He has been behind bars since March, 2019.