A woman who says she was raped by two strangers while drunk now faces the prospect of giving evidence again after an appeal court quashed the conviction of the two alleged attackers, on the grounds they were "racially stereotyped" by the prosecution.

The two men, of Middle-Eastern background, were accused of using the popular Perth nightspot of Northbridge as their "hunting ground" before driving to a nearby park where it was alleged they assaulted the then 25-year-old woman.

The District Court was told during the initial trial that the woman had been out with friends and had consumed at least six drinks.

She was approached by the two men while sitting alone, leaning against a wall outside a hotel.

She said she only had flashes of memory, which included being raped in the back seat of a car, with her head against the door, and glimpses of trees through the window, making her think she was in Kings Park.

She was found wandering in Northbridge by a passer-by who found her in a "distressed state", crying and shaking.

She told him she had been raped and he accompanied her to a police station.

Accused thought sex was consensual

One of the accused, whose name has been supressed and is known only as "MAM", told police he and a friend approached the girl to check if she was ok, as she looked distressed.

He said he "cracked some jokes" and made her laugh.

He said she seemed to have been drinking but her speech was not slurred, and she had no trouble getting into his car. They drove to nearby Kings Park.

The accused said she came onto him in the car at the park. He said the girl then started "making out" with his friend "SF".

He said she then had sex with his friend, SF, after MAM left the car. MAM then returned to see if she was still "up for it" with him, and they had consensual sex.

MAM initially denied he knew the girl or had sex with a woman in the back of a car when questioned by police.

The two men were convicted, but that has now been overturned on appeal and a retrial ordered.

'Lone, vulnerable animal' targeted

During the trial, the prosecution argued the men "picked out the drunkest, most vulnerable animal", a "lone drunk female".

"They are trawling around Northbridge, looking for the drunkest single lone female, and for one purpose — and one purpose only — and that's to have sex with her," the prosecution said. "These two men have nothing to drink, so there's no excuse that, 'Oh, we were drunk,' or something. They're stone cold sober, on the hunt."

He also said:

"They're like vultures or they're like a hyena on the savannah in Africa waiting to pick on the most vulnerable animal, helpless, lost and alone. "And here, that is the drunkest lone female they can find.

Again what you make of them is entirely up to you but obviously [MAM] has a very different side — (from the) side to women in his community and that's the point. He's respectful, he's not physical because there are rules and he abides by the rules within his community, no sex before marriage and he abides by that with those girls. But this is not those girls within his community, this is a white, single, drunken female. Very different rules apply; very different rules."

On appeal, concerns were raised that the description of "predatory" behaviour of the two men was inflammatory, and that the terminology could evoke "emotion and prejudice".

"On at least four occasions the prosecutor resorted to the language of predation, including the words 'predator' to describe each accused, and the word 'prey' to describe the complainant," Chief Justice Wayne Martin found.

He argued that evoking the analogy was prejudicial — and comparing the men to hyenas and vultures was "ill-advised" and could evoke "notions of racial prejudice against the accused and sympathy for the complainant".

Lebanese gang rapes evoked by comments

There were also concerns raised over the prosecution's remarks that the defendants were "respectful of Middle-Eastern women" but "sexually preyed upon women outside of that community".

Justice Martin said the assessment risked evoking cultural stereotypes arising from sensational media reports of rapes committed by young Lebanese men in Sydney.

He also said the prosecutor's comments implied that the accused, perhaps with other friends of Middle Eastern origin, were in the habit of engaging in predatory behaviour in the form of having sexual relations with women who were too drunk to resist.

The judge said there was no evidentiary basis whatsoever for that proposition.

Justice Martin also raised concerns over the prosecution's "mockery" and "sarcastic" remarks — by describing one of the accused as "a gentleman".

The judge said sarcastic comments by the prosecution included the characterisation of the situation as "very romantic, boy meets girl", and that the accused "lifted her mood with that three minutes of sparkling conversation and wit".

It was argued that the prosecution's argument was weak and with the woman unable to say "emphatically" if she had consented to sexual activity or not, or if the woman was unable to give consent due to being intoxicated.

Justice Andrew Beech agreed with Justice Martin's decision. However a third justice, Stephen Hall, agreed a retrial was needed, but did not consider the language of predation used by the prosecutor was intended to, or had the capacity to invoke racial stereotypes.

"That language was, nonetheless, inappropriate in the circumstances of this case," Justice Hall said.

"It was used to reinforce the false line of reasoning, namely that the appellants had gone to Northbridge for the purpose of having sexual relations with a woman who was incapable of consenting and that this was a matter from which lack of consent could be inferred."

The court has ordered a retrial.