Schneier on Security: Automatic License Plate Scanners: "Like the license-plate scanners, the electronic footprints we leave everywhere can be automatically correlated with databases. The data can be stored forever, allowing police to conduct surveillance backwards in time.

The effects of wholesale surveillance on privacy and civil liberties is profound; but unfortunately, the debate often gets mischaracterized as a question about how much privacy we need to give up in order to be secure. This is wrong. It's obvious that we are all safer when the police can use all techniques at their disposal. What we need are corresponding mechanisms to prevent abuse, and that don't place an unreasonable burden on the innocent.

Throughout our nation's history, we have maintained a balance between the necessary interests of police and the civil rights of the people. The license plate itself is such a balance. Imagine the debate from the early 1900s: The police proposed affixing a plaque to every car with the car owner's name, so they could better track cars used in crimes. Civil libertarians objected because that would reduce the privacy of every car owner. So a compromise was reached: a random string of letter and numbers that the police could use to determine the car owner. By deliberately designing a more cumbersome system, the needs of law enforcement and the public's right to privacy were balanced.

The search warrant process, as prescribed in the Fourth Amendment, is another balancing method. So is the minimization requirement for telephone eavesdropping: the police must stop listening to a phone line if the suspect under investigation is not talking."

(Via Schneier on Security.)