Facing opposition from Chinese citizens and foreign governments, Beijing has postponed a plan to reinforce the "Great Firewall of China." These efforts, ostensibly to protect against pornography, look more like a new campaign to crack down on dissent. One way to protest them is to demand that China respect its international trade obligations. While such a premise lacks the moral force of past appeals to human rights commitments, it may prove more effective.

The Beijing government has long sought to control citizens' access to information. That challenge has become more difficult when any individual with a computer (or mobile phone) can access the Internet. Chinese companies have been developed to compete with foreign online search engines and network entities like Yahoo! and Google, both to promote national champions as well as to ensure that Beijing has more say over their policies and practices. The prospect of losing business — a potential market of hundreds of millions of consumers — helps bend foreign companies to the Chinese government's will.

The temporarily shelved plan would have had filters built into Internet servers and search engines in China that block access to Web sites or terms that Beijing deems sensitive. Trying to get information about "Falun Gong," for example, would have been fruitless. Web sites like YouTube are routinely cut off. Chinese Net users have even lost access to iTunes, Apple Computer's popular music Web site, because of concerns over lyrics.

Such crude censorship is hard to justify, so the Chinese government has sought more acceptable rationales. In recent weeks Beijing has launched a new effort to control what users can see while surfing the Internet. In May, it ordered that all new computers sold in China after July 1 have the filtering software called "Green Dam Youth Escort." It was intended to prevent children from accessing pornography or other harmful content.

On June 25 the Chinese Health Ministry announced that it would restrict access to medical research papers on sexual subjects as part of the same campaign. At the same time, Google has been forced to disable a function that lets it suggest search terms, again, in the name of fighting pornography.

Protecting children is good policy, but these measures, if implemented, would be very troubling. Take Green Dam, for example. It is not clear which "offensive" search terms will be filtered. Moreover, there were indications the list would be updated or controlled externally, allowing the government to add politically sensitive words or phrases, such as "Dalai Lama" or "democracy movement," to its list of proscribed terms.

Meanwhile, security experts have concluded that the filtering software itself is so poorly designed that it can easily be hacked, giving outsiders the ability to turn computers installed with the software into "netbots" — machines that the outsiders control.

The evidence marshaled to justify the latest security measures was also suspect. For example, a "student" in a Chinese television interview — who had complained about pornography on the Net — was later discovered to be a station employee. A supposedly impromptu search on Google brought up an "offensive" but unlikely term, suggesting that the term had been deliberately used repeatedly in Google searches just days before the intended ban to make it more likely to appear when a certain word was queried.

Even more disturbing were indications that these efforts were part of a broader crackdown on free speech in China. Increasing numbers of prodemocracy dissidents have been arrested in recent months. Lawyers who agreed to represent clients in human rights cases have had their applications for license renewals — normally an automatic process — denied. Publications that challenge or even question government policies have been shut down.

If Beijing revives demand that the new software be installed, there are commercial grounds on which to challenge Beijing's move. The U.S. government has insisted that the software is "a serious barrier to trade" and inconsistent with World Trade Organization rules. In a letter to the Chinese government, U.S. Trade Representative Ron Kirk argued that "Protecting children from inappropriate content is a legitimate objective, but this is an inappropriate means and is likely to have a broader scope."

Moreover, the restriction of Google's search capabilities smacked of an attempt to level the playing field with homegrown search engines that already dominate the domestic market. Google's access to non-Chinese sites, which was the target of the postponed edicts, had given it an advantage over the Chinese competition. China, like other repressive governments, may try to block the flow of information, but the demands of a modern economy, as well as the curiosity and creativity of its citizens, will make that impossible. The Great Firewall of China, even if put into use, is likely to prove no more successful than its brick-and-mortar namesake.