Exclusive: Microsoft Bing’s censorship in China is even “more extreme” than Chinese companies’

Bing’s censorship rules in China are so stringent that even mentioning President Xi Jinping leads to a complete block of translation results, according to new research by the University of Toronto’s Citizen Lab that has been shared exclusively with Rest of World.

The institute found that Microsoft censors its Bing translation results more than top Chinese services, including Baidu Translate and Tencent Machine Translation. Bing became the only major foreign translation and search engine service available in China after Google withdrew from the Chinese market in 2010.

“If you try to translate five paragraphs of text, and two sentences contain a mention of Xi, Bing’s competitors in China would delete those two sentences and translate the rest. In our testing, Bing always censors the entire output. You get a blank. It is more extreme,” Jeffrey Knockel, senior research associate at Citizen Lab, told Rest of World.

Citizen Lab’s report found last year that alongside Bing’s translation service, its China-based search engine also censors more extensively than Chinese firms’ services do. The studies challenge the popular belief that U.S. tech giants might resist Chinese censorship demands more strongly than their Chinese counterparts. Microsoft has not responded to Rest of World ’s requests for comment.

Microsoft’s practices “harm people’s ability to communicate with an entire demographic of people,” Knockel said.

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Microsoft has operated in China for more than 20 years; the Windows operating system has captured more than 80% market share in the country. Baidu leads as China’s most popular search engine, with more than 50% market share, while Bing has about 25%, according to Statcounter. Both services integrate translation services into their search platforms.

Citizen Lab’s findings are likely to fuel U.S. policymakers’ scrutiny of Microsoft’s operations in China. Following a Bloomberg report in March, which cited Microsoft insiders acknowledging an inclination to “overfilter” China-based search results, U.S. senator Mark Warner called for Bing’s withdrawal from China.

Recently, Microsoft president Brad Smith testified at a U.S. congressional hearing, addressing lawmakers’ concerns after alleged China-linked hackers accessed federal emails hosted by Microsoft. Smith told the Homeland Security committee that the company has refused requests from the Chinese government to hand over data in the past but did not offer details.

The Citizen Lab study is the first to compare censorship between automated translation software offerings for China-based users. Online and print translations in China have long been subject to laws governing the publication of translated texts. Those include a 1997 law on the protection of computer networks with “international interconnections” and the 2017 Cybersecurity Law , which clarified responsibilities for Chinese network operators to comply with national security laws.

Historically, people in China with the ability to translate Chinese into different languages have engaged in translation as an act of resistance against censorship — enabling the spread of information about local events globally. The censorship of translation software has curtailed options in this avenue, Knockel said.

Microsoft has long held the position that pulling its internet services out of China would deny the Chinese people an “important avenue of communication and expression.”

Citizen Lab’s study compared Bing with translation services from Chinese tech giants Baidu, Alibaba, Tencent, and NetEase. The study paper will be presented on July 15 at a FOCI (Free and Open Communications on the Internet) forum.

The report analyzed 10,000 unique censorship applications across the five translation services and identified patterns in how each platform censored results. Bing is the only China-based translation service to consistently produce blank outputs. Translations from Baidu, Tencent, and NetEase silently omit triggering sentences. Alibaba was the only provider to display an error message when sensitive text is inputted, but it will still translate content once the user removes the triggering text.

Independent tests conducted by Rest of World using a VPN mimicking the experience of a user based in China corroborated these censorship patterns.

Microsoft’s broad approach to censoring content on its Bing translation service mirrors its policies on the Bing search engine. Citizen Lab’s report in 2023 found that Bing goes further in censoring results compared to major Chinese search engines, attracting widespread media attention .

Citizen Lab conducted an updated analysis of Bing search censorship results for Rest of World. Bing continues to block a greater number of website domains than its competitors do, meaning that in cases where Baidu’s search results derive from a restricted number of websites, Bing displays results from an even more restricted set of sources (mostly Chinese state media). An independent review by Rest of World confirmed these findings.

“The takeaway for Bing is that they overcensor compared to Chinese technology companies,” said Knockel. “Microsoft doesn’t seem to want to put as much time into developing censorship rules as their competitors. … Bing has more general censorship rules probably because they don’t have the time to keep lists up to date.”

“On the other hand,” Knockel said, “when it comes to translations, Bing is arguably being more transparent that censorship is happening. When other companies translate some sentences but quietly leave out others, users could be none the wiser.”

Benjamin Fung, a McGill University professor and expert on AI and cybersecurity technology, said Microsoft appears to be playing it safe to avoid Chinese government backlash. “On a technical level, censoring more is easier to achieve. They don’t have to detect exactly which phrase is sensitive. The software just has to make the binary decision: translate or not translate,” Fung told Rest of World.

Chinese firms likely have access to more Chinese-language data, enabling more precise censorship, Fung said. They also face greater risk of “angering customers in their primary market” with incomplete translations or heavily censored search results. Baidu, Alibaba, Tencent, and NetEase did not respond to Rest of World ’s requests for comment.

Despite heightened political scrutiny, Microsoft may have recently expanded its China-based censorship. Newly discovered censored terms on Bing’s search engine include references to the September 2023 arrest of Chinese dissident Zheng Baocheng and the Bluebird Movement protests in Taiwan just last month, according to Citizen Lab.

“Right now there is a lot of scrutiny in Washington on companies like Microsoft that serve both U.S. government markets and have deep connections to China. At the same time, the Chinese government is putting more pressure on foreign companies’ content controls,” said Samm Sacks, senior fellow at Yale Law School’s Paul Tsai China Center, whose research focuses on China’s technology policies. “Companies like Microsoft have been trying to thread the needle for a long time. There's not really a needle to thread anymore. You either comply with Chinese laws or not, and Microsoft has made the calculus that it is what they have to do to stay in China.” ▰

Joanna Chiu is the China Editor at Rest of World.