The U.S. Department of Justice on Wednesday asked a federal judge to compel Google to turn over records that detail millions of Internet searches. The DoJ argues that the information is needed to defend a controversial anti-pornography law.

The DoJ says it is seeking Google's data in an effort to show that the Child Online Protection Act (COPA) does not violate the Constitution. COPA was enacted in 1998 to shield minors from sexually explicit material online and suspended that same year when a federal court in Pennsylvania granted an injunction following a suit by The American Civil Liberties Union.

According to the DoJ filing with a San Jose, Calif., judge, the government wants Google's data to help "support its contention that COPA is more effective than filtering software in protecting minors from exposure to harmful materials on the Internet." The DoJ says that to make its case, it has issued subpoenas to Google and "to other entities that operate search engines."

Those other entities are AOL, MSN, and Yahoo, says DoJ spokesman Charles Miller.

Google is fighting the subpoena, which the DoJ issued last year.

According to the court filing, "The government has issued subpoenas to, and has received compliance from, other entities who operate search engines, and each of those entities has produced electronic files to the Government ... that do not contain any additional personal identifying information."

Yahoo complied with the DoJ's request, although it did not provide any personal information about its users, said company spokesperson Mary Osako. "We are rigorous defenders of our users' privacy. We did not provide any personal information in response to the Department of Justice's subpoena. In our opinion, this is not a privacy issue," she said in an E-mail.

DoJ spokseman Charles Miller echoed Yahoo's contention that the data sought doesn't include personally identifiable information.

The government initially asked for two sets of data. First, a file containing all "URLs that are available to be located through a query on your company's search engine as of July 31, 2005." Following discussions with Google, this request was narrowed to "a multi-stage random sample of one million URLs."

Second, the government asked for all "queries that have been entered on your company's search engine between June 1, 2005 and July 31, 2005, inclusive."

The DoJ said in the filing: "The production of those materials would be of significant assistance to the Government's preparation of its defense of the constitutionality of this important statute."

In a statement opposing the DoJ demands, Google associate general counsel Nicole Wong said, "Google is not a party to this lawsuit and their demand for information overreaches. We had lengthy discussions with them to try to resolve this, but were not able to and we intend to resist their motion vigorously."

John Battelle, an online publishing entrepreneur and author of "The Search: How Google and Its Rivals Rewrote the Rules of Business and Transformed Our Culture," expects that the federal government will make more such requests of search engines.