Wrong numbers?

YOU CAN LEARN A LOT ABOUT people from their phone records -- which takeout pizza they like, when they’re likely to be at home and, most relevant to the National Security Agency, who their friends are. Whether the records can lead the NSA to any terrorist cells, however, is an open question.

Few people outside the agency know exactly what data are being collected and how the numbers are being crunched. Still, there’s ample reason to be troubled by the prospect of the feds vacuuming up this kind of data with no court supervision.

The most recent allegations came from USA Today, which reported that the NSA has assembled a massive database of records from U.S. phone lines and is analyzing it for clues about terrorists. This kind of analysis, called data mining, is an outgrowth of the digital age penchant for collecting, storing and analyzing information about everything from grocery store purchases to crime trends.

The calling records kept by phone companies may not provide much more than the numbers dialed, the time and duration of the call and (in the case of mobile phones) the locations involved. If that’s all the database holds, mining it wouldn’t reveal much beyond the clusters of phone lines whose users are associated with one another, and maybe a pecking order within those numbers (A always calls B, but B never calls A).

But it would be child’s play to combine those records with reverse phone directories, credit reports and other widely available databases to yield a much more revealing portrait of the people and places behind the numbers.

Even with the extra information, the analysis may not reveal much about the why behind the social networks it identifies. As a result, the Baltimore Sun and the New York Times have reported, the NSA’s research has produced a lot of leads that go nowhere.

That’s not to say the tools won’t work. Better data, particularly about call content or Internet activity, could help focus the search results on more likely suspects. The more information tapped by the NSA, however, the more intrusive the program becomes. That intrusion is all the more disturbing because the Bush administration refuses to submit any part of the program to judicial oversight.

The Sun also reported that the NSA has abandoned data-mining techniques that would provide not only more protection for individuals’ privacy but a better evaluation of their effectiveness. Such techniques are designed to keep call records anonymous until they are linked to suspected terrorists.

If the feds are going to mine every citizen’s records in search of suspicious patterns, the least they can do is use tools that minimize the exposure of the innocent. Better yet, they should have the courts set the threshold for when the identities behind phone numbers are revealed.