BEIJING — A California software company has sued two Chinese technology firms, charging that they stole its computer code to make an Internet-monitoring program that China’s government sought to install on every computer in the country last year before backing down.
Cybersitter’s lawsuit also names as defendants seven Asian computer makers — including Sony, Lenovo and Acer — accusing them of willingly joining a Chinese government scheme to spread the software, known as Green Dam Youth Escort, throughout the country. The Chinese government was also named as a defendant.
Cybersitter said the two Chinese software companies had pirated 3,000 lines of its code to create Green Dam, which was ostensibly designed to block Web sites that featured pornography and violent content.
But critics and computer experts said the Chinese version was also tailored to enable Chinese government censors to block some political and religious speech and other content, such as references to the 1989 Tiananmen square protests, that the government deemed unsuitable.
Cybersitter’s suit, filed Tuesday in the U.S. District Court for California’s Central District, alleges that the pirated lines of code “include the heart of Cybersitter software: its proprietary content filters” that instruct a computer to block sites containing banned keywords.
The principal defendants, Zhengzhou Jinhui Computer System Engineering Ltd. and Beijing Dazheng Human Language Technology Academy Ltd., developed and marketed the software. They could not be reached for comment on the lawsuit. Lenovo, China’s largest computer maker, said it does not comment on pending litigation.
Each of the computer makers complied with a Chinese government requirement to install Green Dam on new computers, or to include a CD containing the program with each new computer. The lawsuit alleges that the computer makers eventually found out that the software included pirated code, but continued to comply with the government directive for fear of losing market share if their computers were banned in China.
The government originally sought to require that Green Dam be installed on every new computer sold in China. But authorities backed down last summer after an outcry from computer users, from ordinary web surfers to businesses, that saw the software as a threat to their free-speech rights and their computer security.
Some analysts had expressed fears that the software included “back doors” that might allow outsiders to see computer users’ files. Others said the software was so poorly designed that crashes and other problems posed a threat to the security of users’ data.
“They were conspiring to distribute an illegal program to millions of users. They continued to distribute even after everyone knew they were stolen programs,” Gregory Fayer, an attorney for Cybersitter, said in a phone interviewon Wednesday. “There were reports just last week that some of the defendants continue to distribute in China.”
The Chinese companies’ theft was so shoddily executed, Mr. Fayer said, that some of the software code in Green Dam includes announcements directing users to visit the Cybersitter Web site.
China has long been notorious for the ease with which films, computer games, music software and other intellectual property are pirated and sold openly, often on Chinese Web sites that are thoroughly patrolled and regulated by the government. Chinese authorities have made sporadic and unsuccessful stabs at limiting the piracy, but intellectual property rights have become a major point of disagreement between China and some Western nations.
Cybersitter said its $40 software has more than 2.4 million active users worldwide. But in the space of months, the suit alleges, China mandated the installation of the pirated program on 53 million computers designed for home use and a half-million school PCs. The software was downloaded by other users 3,270,000 times, the suit stated.
The suit seeks more than $2.25 billion in damages, a figure attained by multiplying the number of Chinese computers using Green Dam by the price of the Cybersitter software.
David Barboza in Shanghai contributed reporting.
