Collection of evidence is a huge challenge for women who bring lawsuits related to sexual harassment, according to legal experts.

"First, only indecent behavior and rape are crimes under the Chinese Criminal Law, and second, it is difficult to provide conclusive evidence in sexual harassment cases," said Chen Wei, from the Yingke Law Firm in Beijing, who specializes in laws related to domestic disputes and the protection of women.

Sexual harassment is defined as bullying or coercion of a sexual nature, and it can develop into sexual assault, an indecent act or even rape depending on the scale of the offender's behavior, she said, adding that people convicted of minor sexual misconduct only face light administrative punishments, such as being detained for 15 days.

Jiang Yue, a professor of law at Xiamen University in Fujian province, said sexual harassment is a broad concept, but premeditated assault is regarded as a more serious crime than opportunist molestation.

"One of criteria used to determine if an assault is serious is to determine whether someone has made use of special circumstances, such as a team leader-team member relationship, to force others to have sex," she said.

Chen said many of the women who consulted her about sexual harassment were in their 20s and worked for foreign companies.

Their questions mainly focused on how to prove someone's behavior constituted sexual assault and how they could use the law to protect themselves.

"I'd like to help them, but evidence collection is always a big problem," she said. "The police can't detain a person simply because of an accusation, and it is unrealistic to expect a woman to take photos or film an assault."

It is also extremely difficult to prove that the alleged sexual activity was nonconsensual, she added.

Zhou Guangquan, a professor of criminal law at Tsinghua University in Beijing, agreed with Chen's view, but he noted that the alleged victim's level of resistance - including protesting loudly or shouting for help, and how quickly they report the matter to the police - could help to prove that the act was not consensual.

"There is also a statute of limitations related to cases such as this. For example, a woman must report a sexual assault to the police within 10 years or her rights may not be protected. Under the Criminal Procedure Law of the People's Republic of China, it is not possible to bring a case against someone 10 years after the alleged incident if they could face 10 years in prison following a conviction."