It is this variant of this line: "If you've done nothing wrong, you have nothing to fear."
Every time the cops trot out that line, you can figure they're creeping closer and closer to a 1984-level security state.
Then in comments we see this:
The casual attitude of the police toward the privacy of the rest of us, the casual embrace of the notion that the limitations on what they can know about us and our movements are only those of the available technology, are truly chilling.Said license plate readers are generating a huge database of information, with little or no guidelines on usage, strorage, etc. It make me nervous...and I have nothing to hide.