The U.S. government is not powerless to influence China's policies on censoring the Internet. As Google has taken extraordinary steps - bordering on corporate civil disobedience - to challenge China's stranglehold on the flow of information to and among its people, the Obama administration has acted as though its hands were tied. In fact, however, the administration does have options.

One is to file a complaint with the World Trade Organization, contesting China's Internet censorship as a breach of the international trade rules to which China, as a WTO member, is subject. The United States can argue that China's "Great Firewall" - a system of filters and bottlenecks that effectively shutters the country within its own intranet - is an illegal restraint on international trade because it bars foreign companies from competing, via the Internet, in the vast Chinese market.

To understand how this strategy would help Google (and Yahoo, eBay and myriad other U.S. Internet companies that have lived to regret their attempts to do business in China), it's important to understand that Google did not freely choose to build a vast physical presence - complete with office buildings, server farms and thousands of local employees - inside China.

Google would have much preferred to compete in China with a Chinese-language version of its search service operating from servers and offices located safely beyond China's borders (and, in fact, Google built such a site). But Google didn't have that choice because China's firewall effectively prevented it. When not actually blocking access to offshore Web sites that censors deem objectionable, the firewall degrades the performance of Web sites based outside the country.

Non-Chinese Web sites take extra seconds to load, relative to competing sites inside the firewall. In the online world (and particularly in the fast-growing and highly competitive Chinese market), a few seconds might as well be a few extra hours. Google's original Chinese-language site, based offshore, loaded v-e-r-y s-l-o- w-l-y. The Web sites of Google's indigenous Chinese competitors (Baidu, Sina and others) loaded instantly. Google was toast.

As much as any other factor, this performance deficit, a direct consequence of the firewall, forced Google to physically relocate its Chinese language search service inside China, where government bureaucrats could compel Google, upon penalty of withdrawal of its operating license (or worse!), to self-censor its search results. Google knew the risks of its move, and it deliberately and conspicuously sought to mitigate the risks to customers by keeping offshore the Chinese versions of its e-mail business (Gmail), its blogging service, YouTube and other sites consisting mainly of user-generated content.

Because of these effects, China's firewall stands as a barrier to international trade. It halts Internet commerce at China's borders just as surely as a government regulation requiring perishable agricultural exports from the United States to sit for days on China's docks before transhipment to internal distribution facilities. Whether the firewall is a trade barrier that violates international treaties is for administration lawyers to argue to the WTO. The First Amendment Coalition, a nonprofit organization of which I am executive director, has already presented detailed legal briefs on this matter to the U.S. trade representative.

The advantages of a WTO strategy are considerable. WTO sanctions have teeth because they can be enforced through other countries' raising of tariffs against Chinese exports. China in other recent trade disputes has shown that it will abide by WTO rulings it disagrees with (reserving its right to request WTO rulings, to its own benefit, in other matters). For the U.S. government, playing the WTO card also demonstrates seriousness about curbing Chinese censorship, while confining the dispute to an international legal process and avoiding a direct confrontation with China.

Some will argue that the U.S. government has no business pursuing a trade policy that would force China to accept a version of the Internet reflecting freedom of expression. I categorically reject such appeals to "cultural relativism," often made by those who stand to benefit financially or professionally from a close, cooperative relationship with the Chinese government. Aspirations for freedom to speak one's mind, to associate freely with others and to criticize government policies that one views as wrongheaded, are universal.

Google's commendable announcement that it will no longer censor Google.cn, and its threat to quit the China market, have caught Chinese government authorities by surprise, creating an opportunity to apply pressure in a way that could enhance individual liberty for millions of Chinese citizens. It is an opportunity that the Obama administration should not miss.