Congress has been considering requiring Internet service providers to record the activities of their subscribers, store the data and make it available to government officials upon request.

Dragging out the “child porn” red herring again, the Bush administration and Republican members of Congress are pushing for requirements for ISPs to store data on subscribers, all the way up to recording everything each subscriber does online.

The first requirement that law enforcement officials want is for ISPs to keep a record of which Internet address is assigned to which subscriber at what times. Many ISPs reassign Internet addresses to subscribers based on which subscribers are actively using the network at a given time. The practice makes for more efficient usage of scarce addresses, but law enforcement officials complain that it frustrates investigations.

“When subscriber information is not preserved by the ISPs the investigation dead-ends,” Sgt. Frank Kardasz, head of Arizona’s Internet Crimes Against Children Task Force, told CNET News.com. “Ideally, we would like to have ISPs preserve subscriber information for one year.”

And some are going even farther, proposing that ISPs record everything a subscriber does, all the way down to the content of e-mail messages, Web pages and IM conversations.

ISPs complain that such requirements would involve immense costs in building huge data warehouses, that it isn’t clear who would be permitted to access the data under what circumstances, and there isn’t enough evidence that lack of this data actually hinders law enforcement.

A Congressional hearing on the issue is planned for April 27.

The European Union passed a data-retention law, which takes effect in 2008, requiring ISPs to log identifying information about everything users do online and keep the data for a time between six months and two years.