Moving across the country, I had my pot paraphernalia in my car, but no pot. Huge sign before the Kansas line, “Police training ahead. Drug sniffing dogs in use.” I got off and drove through a bunch of dirt roads through corn fields. A cop even drove by me going the opposite direction and waved as he went by. My guess is that it worked so well for them, it went from training exercise to codified practice shortly thereafter.

Traveling on the nearby interstate, drivers would see one of the big lighted signs that said, "Sheriffs Drug Checkpoint Ahead." The sign was a few hundred yard before a remote rual exit. Just out of sight on that exit ramp is where the sheriff and several other agencies set up a "driver's license check." The first time I went through it, I was immediately passed when the dog did not alert and my license showed that I lived on the exit road. They had a school bus, for the people that they arrested and tow trucks for impounded vehicles. The law enforcement officers were visibily having a grand old time; smiles and grins everywhere.

This was maybe 8 years ago, and the "checks" have been halted. I suspect that some judge had a part in that.