Here are some questions and answers on the possible complaint to the World Trade Organization and its chances of succeeding:
What are the Chinese internet controls that have irked Google and the US Government?
Google Inc., the world's biggest Internet search engine operator, in January threatened to retreat from China and shut its Chinese-language search site Google.cn because of hacking attacks on it and other companies that it said came from within China, as well as censorship concerns.
China obliges Internet operators to block words and images the ruling Communist Party deems unacceptable.
Internationally popular websites Facebook, Twitter and YouTube are entirely blocked in China, which uses a filtering "firewall" to block Internet users from other overseas website content banned by authorities.
What would the basis be for a WTO case?
The First Amendment Coalition, a U.S. group that campaigns against censorship, and the European Centre for International Political Economy (ECIPE) in Brussels have presented arguments that Internet censorship by China could violate WTO commitments.
The potential basis for a WTO complaint could be that Chinese Internet censorship discriminates against foreign companies, blocks the legitimate flow of goods and services, lacks transparency and does not offer an acceptable channel to appeal.
These policies violate the General Agreement on Tariffs and Trade, rules about trade in services, and specific rules China agreed to when it joined the WTO in late 2001, the critics argue.
China agreed as part of its commitments to join the WTO that U.S. service companies would have the same access in China as their own companies.
In a paper published last year, ECIPE researchers argued that China may be violating its WTO obligations by entirely blocking some foreign Internet services, such as Facebook and YouTube.
A WTO ruling that rejected a U.S. ban on online gambling services based abroad established the principle that "a total legal ban on a service that affects both domestic and foreign providers is still a quota restriction ... which is against a binding commitment for market access", said the researchers.
How would China respond?
Chinese authorities have not openly responded to U.S. Trade Representative Ron Kirk's latest comments, but a Chinese expert has said such a case has no hope of success.
WTO rules give member states the right to censor the Internet, Zheng Zhihai, general secretary of the China Society of World Trade Organisation Studies, wrote on the China Daily's website on Tuesday.
"If someone intends to challenge China's right to govern its Internet by resorting to WTO rules, they are apparently misguided and bound to fail," wrote Zheng, whose organisation reports to China's Ministry of Commerce.
The WTO has been reluctant to challenge countries' rights to censor content. It ruled last year that China's import monopolies on books, films and other entertainment materials violated market access rules, but upheld its right to censor specific materials.
Critics of China could respond that its Internet censorship is too sweeping and secretive, lacking proportionality and legitimate channels for appeal.
But an expert on China and WTO said a decision on that case would be difficult to enforce, even if Washington won.
"Even if they win, they are going to have an empty victory which they could not enforce," said Henry Gao, a law professor at Singapore Management University.
Where could this could go?
This case could have more impact as a negotiating pawn than a formal legal action.
A U.S. official said earlier that the arguments about taking China to the WTO over online censorship are complex and far-reaching.
Such a case is not a certainty, and it could take years to work through the WTO system of hearings and appeals.
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