The New South Wales Government has referred the state's consent laws to the Law Reform Commission, following a Four Corners investigation into a high-profile sexual assault case.

Sydney man Luke Lazarus was found not guilty of sexual assault, despite a jury and two judges finding that 18-year-old Saxon Mullins had not consented to sex with him in an alleyway behind his father's Kings Cross nightclub in 2013.

Ms Mullins was a virgin and on her first night out in the nightclub district with a friend.

She has spoken publicly about the incident for the first time, sharing her story with Four Corners in the hope it will provoke a discussion about consent.

"No-one dreams of their first time being in an alleyway with someone whose name they can't even remember. No-one wants that," she told the program.

Mr Lazarus was found guilty and sentenced to five years in prison in his first criminal trial, however a judge overturned that decision on the first appeal.

In the second appeal in November 2017, the Court of Criminal Appeal found that while the judge in the second trial erred, Mr Lazarus would not be retried because it would be unfair to put him through a third trial.

Ms Mullins' story, and how it was impacted by complicated and nuanced laws around consent, has disturbed New South Wales Attorney-General Mark Speakman who has now referred the laws to the Law Reform Commission.

Sorry, this video has expired NSW Government directs Law Reform Commission to review consent laws

"[Saxon Mullins has] been humiliated in an alleyway at the age of 18, she's had to tell her traumatic story in court, she's had to face two trials, two appeals, and still, no final outcome," Mr Speakman said.

"From her viewpoint, the whole process has been, I imagine, just a huge disappointment.

"What this shows is that there's a real question about whether our law in New South Wales is clear enough, is certain enough, is fair enough. That's why I've asked the Law Reform Commission to look at the whole question of consent in sexual assault trials."

Mr Speakman wants the commission to look at best practice and law in other Australian and international jurisdictions.

"And importantly to consult all stakeholders, but, in particular, survivors," he said.

In coming weeks he will make a recommendation to the Government about appointing an additional commissioner with criminal law expertise.

'Make no assumptions'

The key message the investigation drove home was the need to explicitly ask for permission to have sex, said the NSW Minister for the Prevention of Domestic Violence and Sexual Assault Pru Goward.

"If it's not an enthusiastic 'yes', then it's a 'no'," she said.

"I feel that this is where the law in NSW needs to go, that's certainly the case in Tasmania and I'm hopeful that the Law Reform Commission will come to a similar conclusion."

Sorry, this video has expired Former Supreme Court judge explains NSW consent laws

Ms Goward said it was not enough for people to assume that because a sexual partner does not say 'no', they have said 'yes'.

"So education needs to stress to young people that you can make no assumptions about what the other person is thinking from what you believe their behaviour is telling you," she said.

Former NSW Supreme Court Justice Anthony Whealy QC hopes the state moves towards a "free agreement" model of consent laws, like Tasmania and Victoria.

"The judge is asked to direct the jury that if the complainant said or did nothing at the time of the sexual intercourse, that means she did not give her free agreement.

"So it's quite stringent, it's a real change in the way a jury would be asked to look at this complicated circumstance. It's really saying if she hasn't said 'yes', she's said 'no'."

Ms Mullins and Mr Lazarus met on the dancefloor at Soho nightclub and she said minutes later he asked her to go to a "VIP area" but instead took her outside to a dark alleyway.

Luke Lazarus believed Saxon's silence indicated consent.

Ms Mullins said he told her to get on her hands and knees in the gravel and had anal sex with her.

"You know, there wasn't any request - it was a demand ... From someone I had never met before. In a dark alleyway. Alone. And I was scared," she said.

During his first trial, Mr Lazarus testified he did not swear or raise his voice at Ms Mullins and he honestly believed that she was consenting.

In the second trial, Judge Robyn Tupman found that Mr Lazarus had no reasonable basis for believing Ms Mullins had not consented, but that Ms Mullins, in her own mind, had not consented.

"Whether or not she consented is but one matter. Whether or not the accused knew that she was not consenting is another matter," she said.

Ms Mullins said the Attorney-General's decision to refer the relevant consent laws to the Law Reform Commission "makes me feel like I did this for a reason. It wasn't all for nothing".

"Maybe someone else won't have to spend five years fighting to get nowhere," she said.

Mr Speakman commended Ms Mullins for speaking out about her ordeal.

"This young woman's bravery in coming forward and sharing her story is commendable. The delay and uncertainty in this matter was unacceptable," he said.