"This is the camel's nose under the tent for using search engines and all kinds of data aggregators as surveillance tools," said Jim Harper of the libertarian Cato Institute who also runs Privacilla.org, an Internet privacy database.
The Bush administration is already under fire from a number of rights groups over security measures it has taken since the Sept. 11, 2001, attacks on America, including pursuing checks on library records and eavesdropping on some telephone calls.
In court papers filed Wednesday in U.S. District Court in San Jose, Calif., the Justice Department stated thatissued last year for 1 million random Web addresses from Google's databases as well as records of all searches entered on Google during any one-week period.
The government said it needed the information to prepare its case to revive the 1998 Child Online Protection Act, which the Supreme Court blocked from taking effect two years ago.
The law prohibited Internet companies from knowingly making available obscene or pornographic material to minors. The Supreme Court said there were potential constitutional problems with the law and sent the case back to a lower court for consideration. It is expected to be heard later this year.
The Justice Department said Friday that America Online, Yahoo and Microsoft had all complied with similar requests.
Attorney General Alberto Gonzales rejected concerns that the subpoena might violate individual privacy rights.
"We're not asking for the identity of Americans. We simply want to have some subject matter information with respect to these communications. This is important for the Department of Justice and we will pursue this matter," he told reporters.
A Google representative said the company objected to the breadth of the government's request but did not consider it to be a privacy issue since the search terms would not include personally identifiable details.
But others were not reassured. Massachusetts Rep. Edward Markey, the ranking Democrat on the telecommunications subcommittee of the House Energy and Commerce Committee, said he would introduce a bill to strengthen consumers' Internet privacy by prohibiting the storage of personally identifiable information in Internet searches beyond a reasonable time.
"Internet search engines provide an extraordinary service, but the preservation of that service does not rely on a bottomless, timeless database that can do great damage despite good intentions," Markey said.
Chris Jay Hoofnagle of the Electronic Privacy Information Center worried that the government.
"If Google hands over the search logs and the Justice Department finds search strings like 'child porn' or 'naked children,' could they not then go back and ask Google for the user's Internet address?" he said.
Ari Schwartz of the Center for Democracy and Technology said he was glad Google was fighting the case but the company needed to make privacy a more fundamental part of its products. He said the case was a wake-up call to all Internet users that information was being collected on them all the time and was stored indefinitely.
Danny Sullivan, an Internet consultant who created Search Engine Watch, said in a posting on his site: "Such a move absolutely should breed some paranoia. They didn't ask for data this time, but next time, they might."
On the other side, the Cincinnati-based National Coalition for Protection of Children and Families, a Christian fundamentalist group, said search companies should be willing to help the government defend children from pornography.
"I'm disappointed Google did not want to exercise its good corporate branding to secure the protection of youth," said Jack Samad, the group's senior vice president.