"When this information is not stored, it may be impossible for law enforcement to collect essential evidence," Deputy Assistant Attorney General told the Senate Judiciary Subcommittee on Privacy, Technology and the Law.

Sen. Al Franken, D-Minn., isn't buying any of it. , he said, to discuss the right of mobile users to know "who has their information and what they're doing with it."

Franken fans from the Jurassic Era of NBC's Saturday Night Live remember him with a satellite dish strapped to his head. Despite his early embrace of location-based technology, Franken showed he's no fan of tracking features.

At the same hearing, a representative of the Federal Trade Commission said the FTC believes wireless carriers and device manufacturers should track only the data needed to provide a service or complete a transaction.