Yes, I have seen these in effect up north here in Canada.
Actually, funny enough.. It run's CPIC up here and everytime I pass one I would be pulled over; as I have been blackflagged "HATES POLICE" (I only know this because of listening to the police radios).
Needless to say I no longer drive, and I still hate police.
On the topic of searches, had a search warrant done at my previous residence and my car.
You cannot hide anything short of a thumbtack away from the 5-0 if they have a team of dilligent officers.. They even used laser measuring devices to map out the house and ensure no false walls.. My charges were not drug related..