Witnesses testifying before a House panel Tuesday on how to combat Internet child pornography differed on how long Internet service providers and cell phone carriers should be required to retain data that could aid investigators.

Deputy Assistant Attorney General Jason Weinstein told the House Judiciary subcommittee on Crime, Terrorism, and Homeland Security said that a uniform standard on data retention is necessary.  But while he and other witnesses agreed that Internet crimes involving minors should be a top priority, they did not agree on how long the ISPs and phone carriers should have to retain data.

Six to 18 months was the recommendation of John Douglass, the chief of police in Overland Park, Kan., who is chairman of the Mid-Sized Cities Section of the International Association of Chiefs. Douglass was responding to a question from freshman Rep. Tim Griffin (R-Ark.).

Other witnesses included the Executive Director of the United States Internet Service Provider Association, Kate Dean, and the General Counsel for the Center for Democracy and Technology, John Morris Jr., whose organization focuses on law enforcement compliance and security issues of concern to ISPs.

Despite questioning from several subcommittee members, Weinstein didn’t offer any specific numbers on retention times or specific solutions on how to combat premature deleting of potentially useful phone and Internet records.

Morris concluded that such a mandate would raise a number of growing concerns about privacy, identity theft and the misuse of personal data, and that Congress should be very hesitant to require mandates involving day-to-day activity.”

The  proposal would force law enforcement to retain any data from most Web sites and online services including all Web 2.0 sites, all social networking sites, all blogs and almost all modern news sites, he said.

The panel’s ranking Democrat, Bobby Scott of Virginia, pushed Morris on how costly it would be to create and maintain data retention databases, but Morris could not pinpoint dollar amounts.

Dean proposed data preservation, which is specific data-saving for a certain time in response to a law enforcement request, as more cost-effective than data retention,  the automatic archiving of data. The Stored Communications Act of 1996 allows law enforcement to require service providers to preserve records or other electronic evidence. Once requested, the records are kept for 90 days and can be renewed.

The drawback, Weinstein said, is that investigators have to request the information on a case-by-case basis, assuming they know the records are relevant to their case before the provider deletes them. ISPs have also been inconsistent in their cooperation, making things more difficult for investigators, and there is no standard time requiring them to hold on to the records before destroying them.

Data retention, however, requires ISPs to automatically store information, allowing law enforcement to gain access to records without having to request them during a specific time window before the ISPs delete the data.

The panel Chairman, Rep.  Jim Sensenbrenner (R-Wis.), concluded the hearing directing his message to ISPs on behalf of Dean. Working voluntarily is preferred, but a mandatory solution is not out of the question, he said.