Smash hit

"These search engines are a very tempting target for government and law enforcement," Givens said. "Look at the millions of people who use search engines without thinking of the potential to be drawn into a government drag net."

The subpoenas were a "classic fishing trip" by federal prosecutors, she added.

Thomas Burke, a San Francisco lawyer who has handled several prominent privacy cases, said that many people contacted Google more often than they spoke to their mother. "Just as most people would be upset if the government wanted to know how much you called your mother and what you talked about, they should be upset about this, too," he said.

Pam Dixon, executive director for the World Privacy Forum, warned that the content of search requests sometimes contain information about the person making the query, such as names, medical profiles or Social Security information.

"This is exactly the kind of thing we have been worrying about with search engines for some time," Dixon said. "Google should be commended for fighting this." She warned people to be careful what personal information they entered into search engines.

The Department of Justice argues that Google’s cooperation is essential in its effort to simulate how people navigate the web. In a separate case in Pennsylvania, the Bush Administration is trying to prove that internet filters do not do an adequate job of preventing children from accessing online pornography and other objectionable destinations.

Obtaining the subpoenaed information from Google "would assist the government in its efforts to understand the behavior of current web users, (and) to estimate how often web users encounter harmful-to-minors material in the course of their searches," the Justice Department wrote in its court petition.

Google issued a statement last night promising to fight the case. "Google is not a party to this lawsuit and their demand for information overreaches," wrote Nicole Wong, Google's associate general counsel. "We had lengthy discussions with them to try to resolve this, but were not able to and we intend to resist their motion vigorously."

But Google's vigorous defence of privacy rights in the face of demands from the US government is apparently at odds with the search engine's stance in China.

There, human rights activists have complained that Google collaborates with the Chinese government, which controls the activities of its 111 million web surfers with one of the most stifling internet censorship policies in the world.

Google is locked in competition for the lucrative Chinese market, along with Yahoo and MSN, and the homegrown Chinese search engine Baidu.com.

All the US companies have been criticised for censoring news sites, search engines and weblogs that China's communist government considers subversive or obscene. For example, a web user in China who tried to search Google or Yahoo for subjects such as democracy and human rights would find nothing in his search results.

There was outrage in September when it emerged that Yahoo had supplied details to the Chinese authorities of the personal e-mail account of Shi Tao, a 37-year-old journalist. He was found guilty of "spreading state secrets" and jailed for 10 years, for forwarding to a foreign website a Chinese government circular banning the media from reporting the 15th anniversary of the Tiananmen Square massacre.

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