Does Dressing Up as a Cop, Staging Fake Traffic Stops, Looking for Drugs, and then Keeping the Drugs Violate the Fourth Amendment?

http://volokh.com/2010/08/26/does-dressing-up-as-a-cop-staging-fake-traffic-stops-looking-for-drugs-and-then-keeping-the-drugs-violate-the-fourth-amendment/