Yi, a professor of law at Tsinghua University, found himself at the heart of the controversy when he sparked outrage with a Weibo comment last week, in which he said raping a "bar girl", prostitute or escort was less serious than raping a "good" girl.

His comments came in a reference to a recent high-profile case in which Li Tianyi, son of a well-known People's Liberation Army singer, was accused of raping a woman he said was a cocktail waitress, paid to spend time with male clients.

Yi tried in vain to quell the online outcry by clarifying that he was not saying it was acceptable to rape a prostitute, but that the psychological harm would be lower for a sex worker than for a chaste girl.

While Yi succumbed to the pressure and deleted his comments, experts say his remarks exposed an attitude that is widely held.

"I can't believe a legal expert can speak like that," says Ai Xiaoming, a professor of women's studies at Sun-Yat Sen University and a women's rights activist. "It is totally wrong, and against the law."

Yet Ai is not really surprised, and says that, while not legally enshrined, there is a culture that explains and nurtures Yi's position that certain women are less deserving of legal protection than others.

At the root of China's schizophrenic approach to sexual violence may be, at least partially, a patriarchical society and the legacy of neo-Confucianism.

"Certainly, filial piety and the hierarchical family unit with the male at the apex has, in practice, had the effect of placing women in a role of diminished social power and acquiescence to the masculine role," says Al Anderson, emeritus professor at Indiana University South Bend, who has researched rape in contemporary China extensively.

"In the worst case scenario, this has resulted in a situation that has objectified women as a mechanism for proving masculinity.

"The grounded moral tone in Confucianism, to me, is a good thing; however, when this morality becomes excessively rigid it leads to a too easy condemnation and vilification of those perceived as different, be they the poor, migrants, men who have sex with men, sex workers, or women in general.

"Any social problem then becomes the 'fault' of the individual, not the social determinants that actually caused the problem."

This contributes to a culture of "victim blame" that stretches far beyond the issue of sexual violence, as exemplified also by the government's attitude in the early stages of the mainland's HIV/Aids epidemic.

Yi's opinion is likely to be shared by many others within the judicial system and beyond, says Li Yinhe, a sociologist and sexologist at China Academy of Social Sciences. Women as well as men hold this attitude, Li says.

At first glance, Chinese law appears to embody the egalitarianism that the party propagated when Mao Zedong proclaimed that "women held up half of the sky".

Gender equality and women's rights are stated in the constitution, and the marriage law and the law on the protection of rights and interests of women specifically ban family violence and sexual harassment.

Several policy papers have outlined strategies for development for women and children, and rape is a crime punishable by the death penalty.

This seems a long way from the previous Qing legal code, in place until 1912, under which the chastity of a woman was a prerequisite for sexual violence to be a crime.

In the prevailing "cult of chastity", the burden of proof was exclusively on the woman, who if she had previously had "illicit" - extramarital - sex could not be considered to have been raped. Yet the modern legal landscape may not have fully ridden itself of its past.

"Even if the law doesn't remain, people's thinking does," Li says. "People still like to divide women into two groups - good girls and bad girls."

The latter category, she explains, includes prostitutes, those who have premarital sex and those working in bars. Even as sexual freedom is on the rise - extramarital sex was illegal only 30 years ago - society's attitudes to sex remain contradictory. While many mainland Chinese today have sex before marriage, women are often pressured to preserve the illusion of chastity as many men still prefer marrying a virgin.

For women working in China's sex industry - illegal but endemic - the consequences of the good-girl-bad-girl mindset are immense.

A report in May by Human Rights Watch drew attention to the widespread abuse, including rape, of China's estimated four to six million sex workers. Yet a report of rape is not only unlikely to be taken seriously by the police but also might see the sex worker herself punished.

Experts fear cases such as Li Tianyi's may perpetuate stereotypes that are harmful for women regardless of which category they fall into. While Li's parents claim their son paid the woman he had sex with, her lawyer insists that while she did work in a bar, she was not a prostitute - as if her occupation mattered for the verdict, given it is equally illegal to rape a prostitute.

This emphasis on the victim's - theoretically irrelevant - profession reflects a mentality that makes the survivor, as opposed to the perpetrator, of sexual violence the focal point of the crime.

The patriarchical culture is reflected across society, experts say, not least in a male-centric pornographic industry. Much of the porn on the mainland is violent and occasionally features so-called "rape play".

Officially illegal, adult content remains widely available and surfing for online porn is popular. For many, pornography is still the primary source of sexual education and it remains unclear what impact misogynistic content may have for the incidence of sexual violence.

"I don't think that it has been proven that violent or extreme types of porn or violence leads to sexual aggression," says Katrien Jacobs, a professor at the University of Hong Kong and author of . "But it is true that the Japanese adult video market, which has illegally entered China, is dominated by all kinds of genres that privilege male pleasure by casting women as submissive partners.

"I just hope that China will seek out a balanced porn climate in this respect, and it is up to women to reclaim and produce female-friendly sex entertainment and eroticism."

Sexual violence has come to epitomise a legal system that readily provides the rich and powerful with loopholes.

Many netizens have linked the case of playboy Li with that of a Hainan school principal accused of drugging and molesting six underage girls in a hotel room. They say both cases feature privileged perpetrators and disempowered victims.

Activists had a hard time trying to get the claims against the principal taken seriously after it was reported that officials were trying to cover up the case by stopping the victims' parents from talking to the press.

Earlier this month, officials dumped Ye Haiyan, an activist for prostitute's rights, and her daughter by the side of the road with their meagre possessions after she demonstrated outside the Hainan school while holding a sign saying "principal, get a room with me - spare the schoolchildren".

Rights activist Ai protested by posting topless pictures on social media with the message "sleep with me, release Ye Haiyan" scrawled across her chest, inspiring other internet users to similar acts.

"This is the same thing as the chengguan [urban security workers] who killed the melon vendor," she says, referring to the case last week in Linwu county, Hunan.

At the end of the day, she adds, the concern is more about class injustice than women's rights.

Still, Ai is cautiously optimistic. The recent attention devoted to sexual violence could actually be a good sign, she says.

"At least now the media is covering these issues, and more and more people can use websites, and post comments," she says. "Now, women's rights defenders need to focus on building a new culture. There must be no difference from the victim's identity, occupation or gender."