Earlier this week, Chinese Internet services blocked searches for the phrase mìshū bāng (秘书帮). Roughly translated as “secretaries gang,” the term relates to the speculation surrounding government probes into public officials linked to former security czar and Politburo Standing Committee member Zhou Yongkang, who is reportedly under investigation for corruption. Services such as microblog Sina Weibo and search engine Baidu also blocked keywords related to former Politburo member He Guoqiang after the overseas Chinese muckraking and rumormongering website Boxun published an unverified story alleging corruption.

In news media outside China, discussions of Chinese Internet censorship often center around how Chinese Internet users creatively circumvent filters and blocks, especially when the censorship hides Chinese politicians' graft. While the power of netizens should never be discounted, the cases of Zhou and He illustrate the multiple ways in which Chinese censorship still often manages to succeed by either pushing the agenda of authorities or silencing critical stories.

According to the latest statistics from China Internet Network Information Center (CNNIC), an administrative body under the Ministry of Information Industry, China currently has 618 million Internet users and 281 million use popular microblogging sites known collectively as weibo.

The limits of Chinese information controls have been well reported, with the fury surrounding the suppression of the popular and groundbreaking newspaper Southern Weekly in 2013 and the botched attempt at covering up the fatal Wenzhou train crash in 2011 serving as classic examples of netizens’ successfully thwarting censorship.

In a 2013 study of social media site Sina Weibo, researchers at Northeastern University found empirical evidence that censorship sometimes not only fails to quash discussion of sensitive topics on Chinese social media sites, but may even encourage it. Though numerous factors may be at play, the finding reinforces the popular notion that attempts to conceal information can backfire and even become a central part of a story—a phenomenon known as the Streisand Effect, for singer Barbra Streisand, whose attempts to suppress photographs of her multimillion dollar mansion caused photographs of the house to go viral.

Attempts to censor “secretaries gang” would seem like a prime candidate for the Streisand Effect. The secretaries in the “secretaries gang" are not your typical clerical workers, but rather the powerful associates and protégés of a retired member of China’s most powerful governing body. Whether or not Zhou is formally prosecuted, his current situation makes him one of the highest ranking Chinese Communist Party officials to be disciplined for corruption.

In the past couple weeks, two more of Zhou’s close political associates were detained for investigation for “serious violation of discipline”—a euphemism for corruption. After articles in the China Business Journal described the group as a “secretaries gang,” the term soon appeared in articles in local newspapers, in he Chinese online encyclopedia Baidu baike, and even in the national China Youth Daily, the official newspaper of China’s Communist Youth League.

“Secretaries gang” wasn’t the only phrase censored. Also wiped out were Zhou Yongkang’s name, as well as plays on parts of his name, such as “Master Kang,” the brand name of a popular kind of instant noodles used as code to talk about him online. Even the phrase “instant noodles” (fāngbiànmiàn / 方便面) was filtered from the Chinese Internet, as was, briefly, bāozi (包子)— the word for the steamed stuffed buns President Xi recently bought in public—when talk of the Beijing staple became the online code name for Xi, especially among netizens critical of the leader. The Internet companies censor sensitive microblog posts only partially, allowing, for instance, posts including Zhou Yongkang’s name to appear on individual users’ weibo but making them invisible to the offending user’s followers or to anyone else. Offending material effectively vanishes.

Whereas most censorship alerts the user to its presence with blunt error messages, attempting to instill a chilling effect, this subtler method gives users the mistaken impression of having shared their views with their online followers when, in fact, their messages are only visible on their own computers. Thus, authorities can shut down discussions without raising the specter of netizens outraged that their posts have been deleted.

A post, indicated by a red arrow above, about Zhou Yongkang successfully appears on one user’s microblogging page.

When another user tries to view that same page from his or her computer, the post about Zhou Yongkang is missing.

While none of the official media stories make direct mention of Zhou Yongkang’s name, online speculation is rife that the former security chief is being set up for a fall—speculation reinforced by the censorship. As security czar, Zhou was widely disliked in most sectors and strata of Chinese society and seldom enjoyed much support except from amongst his own associates. Authorities have not publicly addressed Zhou’s status, and according to The Wall Street Journal he has been unavailable for comment.

It’s possible that the search blocks were not ordered by Beijing explicitly, but rather instituted by Internet company executives fearful of being punished by the government as they were during the scandal surrounding Zhou's ally former Chongqing Party Secretary Bo Xilai, who is now serving life in prison.

However, it’s just as likely, given the secrecy surrounding China’s top leaders, that the government directly requested the digital expurgation as part of efforts to manage discussion of Zhou's fate. As the government’s crackdown last summer on online rumors showed, officials are deeply wary of the unpredictable nature of Internet discourse. An attempt to undercut a figure as prominent as Zhou is incredibly tricky for Beijing.

In recent days, authorities appeared to build a public case against Zhou by allowing stories detailing allegations against his circle to spread. Those stories have circulated widely on social media sites, but the corresponding online censorship has helped limit the further spread of damaging chatter and allowed the Communist Party to avoid public discussion about disunity and corruption in the upper ranks.

The absence thus far of widespread online discussion about He Guoqiang shows us just how effective Chinese censorship can be. He Guoqiang may not be as well known as Zhou to readers outside China, but like Zhou, he was a member of the nine-man 17th Politburo Standing Committee (PSC) and he headed the Party’s powerful Central Commission for Discipline Inspection. Though He’s tenure as a rising official in Southeast China’s Fujian province and in the southwestern megacity Chongqing were rocked by scandal, he was never implicated in wrongdoing and served out a relatively understated term in the PSC. Except for a fawning January 2014 cover article in the independent magazine Phoenix Weekly celebrating his filial piety and how his sons’ weddings took place at a simple guesthouse, He appeared to have escaped the scrutiny that befell many of his colleagues. Until, that is, Boxun’s February 14 article threatened to upset the equilibrium by alleging corruption in He’s family.

Boxun often publishes information sent to it anonymously, and other overseas Chinese media say the unverifiable nature of the allegations makes it difficult to treat Boxun’s stories as anything more than rumor. Rumor or not, stories about high-level corruption tend to move quickly through Chinese social media. Yet the He story has gained little noticeable traction.

A number of factors are likely in play, including He's relatively low profile and Boxun’s reputation, but the story's absence is also a sign of the speed at which today’s censors can work. Not long after the Boxun rumor about He surfaced, censors blocked a number of unusually specific terms. Weibo blocked and leading search engine Baidu filtered results for searches for “He Guoqiang” (贺国强) in combination with phrases such as "flees abroad” (外逃 Wàitáo), “daughter-in-laws’ huge fortune” (儿媳巨款 Érxí jù kuǎn), and “enrichment” (敛财 Liǎncái). Censorship-tracking website Fei Chang Dao noticed the names of both of He’s sons were filtered from search results on Baidu (and also blocked on Weibo), but, so far, such censorship has not sparked broad interest among social media users.

It’s impossible to know if He’s story would have gotten more attention, or if online discussions about Zhou would have spiraled unpredictably, if both men’s names had not been suppressed. What is clear is that the censorship did not appreciably hurt He or Beijing—a situation that might change in the future if the number of Internet users documenting and sharing instances of even minor online censorship continues to grow and generate publicity. One should not underestimate the ability of Chinese Internet users to dig up information authorities are trying to hide—especially when it directly affects them or when it relates to righting injustices. But one must also acknowledge that China’s censors often still have the will and the tools to manage online information effectively to suit the government’s needs.