[Reeses]

or even if you were near the scene of a crime

The government already has access to this information via cell phones. When someone changes cells, a computer logs it. The OnStar type systems built into cars are even worse. The government can get a court order to listen in as you drive.

[DB]

Yes, OnStar is bad for a host of reasons.

Cell phones at least are not nearly as accurate as GPS at locating you. General vicinity is about the best they currently do.