[legion]

Two weekends ago (on Martin Luther King day) we drove back from Arkansas. As we neared the St. Louis suburbs, we saw a sign on the interstate, just before and exit that said something like: "Drug checkpoint 1 mile ahead/Drug dogs in use." Of course, one mile down the interstate, there is no checkpoint. There was a similar sign in East St. Louis once we got over the rive, just before an exit, and no checkpoint.

In recalling my case law from college, I seem to remember a case that got to the SCOTUS about this tactic. In this specific example, the police were stopping/searching all cars that got off at the exit--there was no checkpoint on the interstate. I also seem to call that the SCOTUS ruled this tactic was unconstitutional.