Why ex-Illawarra teacher who admitted to sex with a child has been acquitted

But in the eyes of the law she is not guilty of a crime, her conviction quashed on the basis of a legal technicality.

The Court of Criminal Appeal ruled on Friday that the now-77-year-old could not be convicted under the law that was in force at the time of her actions because it only applied to male offenders.

Grant pleaded guilty in 2022 to maintaining an unlawful sexual relationship with a child, a historical charge related to incidents that occurred when she was a teacher at St Paul's Catholic Primary School in Albion Park in the 1970s.

She was subsequently jailed for a maximum term of six years and nine months, with a non-parole period of three years and four months.

A document of agreed facts tendered to the District Court in 2022 detailed 12 specific instances of sexual contact with the boy but said these were representative of many more.

The agreed facts said it began with Grant - a married mother - encouraging the boy to fondle her breasts, before progressing to sexual intercourse while the boy was still in primary school.

In 2021, still suffering the profound impacts of these incidents, the victim went to police.

"I live with permanent pain," the man told the District Court in 2022.

Grant served 14 months' imprisonment before she was released on bail earlier this year pending her appeal.

Grant launched a bid to overturn her conviction after Helga Lam, a former Sydney teacher, had an indictment of 15 charges of indecent assault quashed in February.

Ms Lam was accused of crimes against four boys dating back to 1978, but the law at that time did not apply to acts committed by a woman.

It related to sodomy and male homosexual conduct, so it only applied to sexual acts committed by a male person against another male, even if they were consenting adults.

In the case of Ms Lam, Justice Peter Garling said applying this law to women would potentially criminalise all consensual, private sexual acts a woman carried out upon a man, which would be "absurd".

While Grant pleaded guilty to a different offence, the decision in Ms Lam's case was relevant because the "unlawful sexual acts" that established the "unlawful sexual relationship" were said to have been indecent assaults against a male.

"I am of the view that notwithstanding the egregious and abhorrent nature of the appellant's conduct, the decision in Lam makes it clear that a miscarriage of justice has occurred in this case," Justice Sarah McNaughton said in the Court of Criminal Appeal judgment handed down on Friday.

She said there were no alternative offences available under the Crimes Act, so Grant's sexual acts against the boy did not meet the threshold of being unlawful.

As a result, Grant has been acquitted.

"I must acknowledge the significant distress no doubt being experienced by the victim in this matter, especially where the appellant had admitted to having a sexual relationship with him when he was just a child, and in circumstances where she had pleaded guilty and had been sentenced to a significant custodial penalty," Justice McNaughton said.

"It is an understatement to say that this is a regrettable situation."