Via Hit & Run, a piece in CNET ponders the troubling privacy implications of nascent federal plans to track all vehicles with GPS in order to institute “mileage-based road user fees.”

Details of the tracking systems vary. But the general idea is that a small GPS device, which knows its location by receiving satellite signals, is placed inside the vehicle.

Some GPS trackers constantly communicate their location back to the state DMV, while others record the location information for later retrieval. (In the Oregon pilot project, it’s beamed out wirelessly when the driver pulls into a gas station.)

The problem, though, is that no privacy protections exist. No restrictions prevent police from continually monitoring, without a court order, the whereabouts of every vehicle on the road.

No rule prohibits that massive database of GPS trails from being subpoenaed by curious divorce attorneys, or handed to insurance companies that might raise rates for someone who spent too much time at a neighborhood bar. No policy bans police from automatically sending out speeding tickets based on what the GPS data say.

I’m very much in support of congestion pricing and similar schemes to reduce driving in general and peak-hour driving in particular. But I must confess that my civil-libertarian absolutism twitches at the very thought of this sort of thing. What do y’all think?