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Digital minutiae could be used to track terror networks, but it could produce false positives.

By Mark Clayton, May 12, 2006.

What can the United States government really glean from the phone-call histories - records of who called whom, when, and for how long - of millions of Americans?

After all, it's the same information that has long been available to authorities armed with a subpoena, though not sought en masse until after the 9/11 terror attacks. Its value, say computer experts and others, is that it can be used to identify a "social network" of interconnected people - including, perhaps, would-be terrorists.

"From phone records you can learn who are my friends - and who their friends are - what services I use, where I shop," says Johannes Gehrke, a computer scientist at Cornell University who has written search algorithms for government analysis programs. "Our social interactions leave a digital trail. [Phone-record analysis] is government learning about human behavior from analyzing that trail."

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