The US constitution did not address the matter of privacy, but US legal tradition - over the centuries - has interpreted it to _imply_ such a right, or some kin

The US constitution did not address the matter of privacy, but US legal tradition - over the centuries - has interpreted it to _imply_ such a right, or some kinds of privacy protection. See: https://en.wikipedia.org/wiki/Right_to_privacy#United_States https://en.wikipedia.org/wiki/Right_to_privacy#United_States Also, The search part, and perhaps even the inspection of cars using the cameras, may be considered "unreasonable search" of the kind forbidden in the 4th amendment to the US constitution. Still, remember that both law and policy are made by the state and applied by the state, in the service of state interests, which overlap the interests of subjects only to a limited extent. The US government already basically wiretaps most people's private communications (via Google, Apple, Yahoo, Microsoft etc. - Snowden revelations) - so why not spy on people on the roads?