China's internet censors have consistently blocked content related to a nationwide police operation targeting rights lawyers since it was launched in on July 9, 2015 (709), a Canada-based investigation has revealed.
Researchers at CitizenLab at the Munk School of Global Affairs, University of Toronto found "detailed evidence" that tweets and photos posted to to the popular smartphone chat app WeChat and the Twitter-like platform Sina Weibo were censored with "forbidden" keywords.
"The 709 Crackdown is considered one of the harshest systematic measures of repression on civil society undertaken by China since 1989, and is the subject of much ongoing international media and human rights discussion," CitizenLab's professor Ron Deibert wrote in a blog post launching the report.
"Unfortunately, as our experiments show, a good portion of that discussion fails to reach Chinese users of WeChat and Weibo," Deibert said.
Censors manage to block this content through the use of combinations of banned keywords, which might include the names of key figures in the crackdown, or words describing how it happened.
Images linked to the campaign to raise awareness of the plight of the lawyers, rights activists and their families were also successfully removed from WeChat Moments for accounts registered with a China-based phone number.
Deibert said most of the decisions we make online are guided by invisible algorithms, and that researchers wanted to unmask the mechanisms used to limit what China's 731 million internet users can see if they don't scale the Great Firewall.
"Whether those algorithms are fair or not, whether they respect human rights, whether they make mistakes or not, are all questions that can only be answered if the algorithms can be properly examined," he wrote. "Our research aims to break through that obfuscation and bring such algorithms to account."
More than 300 human rights lawyers, law firm staff and associated rights activists in China have been targeted by police in a nationwide crackdown since July 2015, with family members or released detainees often placed under close surveillance or slapped with a ban on overseas travel.
Four detainees have been convicted, 10 formally charged with various offenses, while another 10 have been released pending further investigation or released on bail.
Guangdong-based rights activist Ye Du said China has led the world in the effective deployment of government internet censorship.
"China has set a precedent for the practice online monitoring and censorship," Ye said. "The government has spared no effort to achieve control of the internet, because the free flow of information is the worst fear of an authoritarian regime."
"Now, they have technological capacity to achieve this, and they continue to pour massive resources into doing this," he said. "I don't foresee any relaxation in future; I think it's just going to get stricter and stricter."
Rights lawyer Chen Jiangang, defense attorney for detained lawyer Xie Yang, said the lack of scope for freedom of expression in China is "pure bullying."
"The law has been a merely cosmetic addition to the line they have been taking all along, which is towards further political repression," Chen said.
"Now, that mask has fallen away and they are just going in for blatant bullying."
Fellow rights lawyer Wang Shengsheng said the ruling Chinese Communist Party is keen to ensure that nobody can use social media to oversee its actions.
"Censorship of public opinion means that the last channel through which the general public could have exercised some kind of oversight [over the government] has now been cut off," Wang said.
"Without any oversight, the government can do what it likes behind closed doors," he said. "But I don't think we can solve problems by relying on their internal self-discipline."
"This is really frightening."
Reported by Xin Lin for RFA's Mandarin Service. Translated and edited by Luisetta Mudie.