Data retention rules could permit police to obtain records of e-mail chatter, Web browsing or chat-room activity months after Internet providers ordinarily would have deleted the logs--that is, if logs were ever kept in the first place. No U.S. law currently mandates that such logs be kept.

In theory, at least, data retention could permit successful criminal and terrorism prosecutions that otherwise would have failed because of insufficient evidence. But privacy worries and questions about the practicality of assembling massive databases of customer behavior have caused a similar proposal to stall in Europe and could engender stiff opposition domestically.

In Europe, the Council of Justice and Home Affairs ministers say logs must be kept for between one and three years. One U.S. industry representative, who spoke on condition of anonymity, said the Justice Department is interested in at least a two-month requirement.

Justice Department officials endorsed the concept at a private meeting with Internet service providers and the National Center for Missing and Exploited Children, according to interviews with multiple people who were present. The meeting took place on April 27 at the Holiday Inn Select in Alexandria, Va.

"It was raised not once but several times in the meeting, very emphatically," said Dave McClure, president of the U.S. Internet Industry Association, which represents small to midsize companies. "We were told, 'You're going to have to start thinking about data retention if you don't want people to think you're soft on child porn.'"

McClure said that while the Justice Department representatives argued that Internet service providers should cooperate voluntarily, they also raised the "possibility that we should create by law a standard period of data retention." McClure added that "my sense was that this is something that they've been working on for a long time."

This represents an abrupt shift in the Justice Department's long-held position that data retention is unnecessary and imposes an unacceptable burden on Internet providers. In 2001, the Bush administration expressed "serious reservations about broad mandatory data retention regimes."

The current proposal appears to originate with the Justice Department's Child Exploitation and Obscenity Section, which enforces federal child pornography laws. But once mandated by law, the logs likely would be mined during terrorism, copyright infringement and even routine criminal investigations. (The Justice Department did not respond to a request for comment on Wednesday.)

"Preservation" vs. "Retention"

At the moment, Internet service providers typically discard any log file that's no longer required for business reasons such as network monitoring, fraud prevention or billing disputes. Companies do, however, alter that general rule when contacted by police performing an investigation--a practice called data preservation.

A 1996 federal law called the Electronic Communication Transactional Records Act regulates data preservation. It requires Internet providers to retain any "record" in their possession for 90 days "upon the request of a governmental entity."

Child protection advocates say that this process can lead police to dead ends if they don't move quickly enough and log files are discarded automatically. Also, many Internet service providers don't record information about instant-messaging conversations or Web sites visited--data that would prove vital to an investigation.

"Law enforcement agencies are often having 20 reports referred to them a week by the National Center," said Michelle Collins, director of the exploited child unit for the National Center for Missing and Exploited Children. "By the time legal process is drafted, it could be 10, 15, 20 days. They're completely dependent on information from the ISPs to trace back an individual offender."

Collins, who participated in the April meeting, said that she had not reached a conclusion about how long log files should be retained. "There are so many various business models...I don't know that there's going to be a clear-cut answer to what would be the optimum amount of time for a company to maintain information," she said.

McClure, from the U.S. Internet Industry Association, said he counter-proposed the idea of police agencies establishing their own guidelines that would require them to seek logs soon after receiving tips.

Marc Rotenberg, director of the Electronic Privacy Information Center, compared the Justice Department's idea to the since-abandoned Clipper Chip, a brainchild of the Clinton and first Bush White House. Initially the Clipper Chip--an encryption system with a backdoor for the federal government--was supposed to be voluntary, but declassified documents show that backdoors were supposed to become mandatory.

"Even if your concern is chasing after child pornographers, the packets don't come pre-labeled that way," Rotenberg said. "What effectively happens is that all ISP customers, when that data is presented to the government, become potential targets of subsequent investigations."

A divided Europe

The Justice Department's proposal could import a debate that's been simmering in Europe for years.

In Europe, a data retention proposal prepared by four nations said that all telecommunications providers must retain generalized logs of phone calls, SMS messages, e-mail communications and other "Internet protocols" for at least one year. Logs would include the addresses of Internet sites and identities of the correspondents but not necessarily the full content of the communication.

Even after the Sept. 11, 2001, terrorist attacks, the Bush administration criticized that approach. In November 2001, Mark Richard from the Justice Department's criminal division said in a speech in Brussels, Belgium, that the U.S. method offers Internet providers the flexibility "to retain or destroy the records they generate based upon individual assessments of resources, architectural limitations, security and other business needs."

France, the United Kingdom, Ireland and Sweden jointly submitted their data retention proposal to the European Parliament in April 2004. Such mandatory logging was necessary, they argued, "for the purpose of prevention, investigation, detection and prosecution of crime or criminal offenses including terrorism."

But a report prepared this year by Alexander Alvaro on behalf of the Parliament's civil liberties and home affairs committee slammed the idea, saying it may violate the European Convention on Human Rights.

Also, Alvaro wrote: "Given the volume of data to be retained, particularly Internet data, it is unlikely that an appropriate analysis of the data will be at all possible. Individuals involved in organized crime and terrorism will easily find a way to prevent their data from being traced." He calculated that if an Internet provider were to retain all traffic data, the database would swell to a size of 20,000 to 40,000 terabytes--too large to search using existing technology.

On June 7, the European Parliament voted by a show of hands to adopt Alvaro's report and effectively snub the mandatory data retention plan. But the vote may turn out to have been largely symbolic: The Council of Justice and Home Affairs ministers have vowed to press ahead with their data retention requirement.