December 4, 2002


SHANGHAI, Dec. 3 -- China has the most extensive Internet censorship in the world, regularly denying local users access to 19,000 Web sites that the government deems threatening, a study by Harvard Law School researchers finds.

The study, which tested access from multiple points in China over six months, found that Beijing blocked thousands of the most popular news, political and religious sites, along with selected entertainment and educational destinations. The researchers said censors sometimes punished people who sought forbidden information by temporarily making it hard for them to gain any access to the Internet.

Defying predictions that the Internet was inherently too diverse and malleable for state control, China has denied a vast majority of its 46 million Internet users access to information that it feels could weaken its authoritarian power. Beijing does so even as it allows Internet use for commercial, cultural, educational and entertainment purposes, which it views as essential in a globalized era.

Only the most determined and technologically savvy users can evade the filtering, and they do so at some personal risk, the study says.

"If the purpose of such filtering is to influence what the average Chinese Internet user sees, success could be within grasp," said Jonathan Zittrain, a professor at the law school and a co-author of the study.

The study offers fresh evidence that the Internet may be proving easier to control than older forms of communication like telephones, facsimile machines or even letters. China can tap some telephones or faxes or read mail. But it cannot monitor every call, fax message and letter.

The Internet, in contrast, has common checkpoints. All traffic passes through routers that make up the telecommunications backbone here. China blocks all access to many sites, and it has begun selectively filtering content in real time -- even as viewers seek access to it -- and deleting individual links or Web pages that it finds offensive.

By regularly testing access to 200,000 popular Web addresses, the researchers found that China blocked up to 50,000 sites at some point in the six-month period. Of those, the study found 19,000 sites that could not be reached from different places in China on multiple days. The study is at

Compared with Saudi Arabia, which the team studied earlier, China exercises far broader though sometimes shallower control. Beijing completely blocked access to the major sites on Tibet and Taiwan. A user who types "democracy China" into Google, the popular search engine, would find nearly all the top sites with those words out of reach. Google itself was blocked in September, although access is now restored.

Chinese users cannot often reach the sites run by Amnesty International or Human Rights Watch. China also does not allow users to connect to major Western religious sites.

News media sites are also often blocked. Among those users had trouble reaching in the test period were National Public Radio, The Los Angeles Times, The Washington Post and Time magazine.

Though China says a main justification for censorship is the proliferation of pornography, its blocking of such sites is less dogged. The study found that China blocked fewer than 15 percent of the most popular sexually explicit sites. Saudi Arabia banned 86 percent of the list.