I don't doubt that the information could be useful to government investigators. Does that fact justify forcing companies to retain it? Such a mandate goes beyond the customary assistance that businesses are required to give in response to a court order. As with the Clinton administration's Clipper chip proposal, the defunct ban on exporting strong encryption software, and the Communications Assistance for Law Enforcement Act (a.k.a. CALEA, which requires telecom companies to make their networks tap-friendly), the government wants to arrange the world to make life easier for law enforcement agencies. Once we accept this demand as legitimate, the only question is how to "balance" privacy interests against the enhanced security promised by unimpeded policing—an inherently subjective judgment that tends to favor the government, since cops can always cite concrete examples of how they would use their new powers for good, while the negative implications seem vague and hypothetical.