Just a year ago, China was ready to put a mandatory content filter called "Green Dam" on every PC in the country. Today, the Green Dam project has been abandoned -- and the Chinese government is being accused of stealing some of the code used to create the software.

Cybersitter, a small U.S. maker of Web security and content filtering software, is suing the Chinese government, two Chinese firms, and seven PC makers over the use of its code in the Green Dam Youth Escort program.

According to news reports, the $2.2 billion lawsuit accuses the defendants of misappropriating trade secrets, unfair competition, copyright infringement, and conspiracy.

The lawsuit, filed in a federal court in Los Angeles, alleges that the Chinese makers of Green Dam illegally copied more than 3,000 lines of code from Cybersitter's filtering software.

No formal response from the Chinese government to the case has yet been reported. Jinhui Computer System Engineering, which makes Green Dam, has previously denied any wrongdoing.

In the suit, Cybersitter says the manufacturers conspired with China's leaders and computer manufacturers to distribute more than 56 million copies of the pirated software. Millions of copies were distributed even after manufacturers became aware of the infringement, the complaint says.

The lawsuit also alleges that the Chinese software makers broke U.S. laws governing economic espionage and trade secrets.

"This lawsuit aims to strike a blow against the all-too-common practices of foreign software manufacturers and distributors who believe that they can violate the intellectual property rights of small American companies with impunity without being brought to justice in U.S. courts," Cybersitter attorney Greg Fayer told reporters.

The Chinese government last year mandated that by July every PC sold in the country was to be supplied with Green Dam. The idea was to stop users from looking at violent or pornographic content.

But widespread disapproval inside China, legal challenges, and criticism over the effectiveness of the software caused the Chinese government to end the mandate.

Analysts at the University of Michigan found weaknesses in the URL, text, and image filtering system, and vulnerabilities in the software that made machines susceptible to being hijacked.

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