A few months back I did quite a bit of research in the legality of this approach. I only found on Texas case (Austin COA)in which the court upheld a stop of a woman who tossed the drugs out of car when she saw the sign warning about a checkpoint ahead. Other federal and state courts have been all over the place on the issue--some finding it illegal; others finding it legal.

Janette Ansolabehere

It seems to me to be pretty hard to argue against the holding in U.S. v. Flynn, 309 F.3d 736 that "The posting of signs to create a ruse does not constitute illegal police activity." The Colorado Court of Appeals accepted this argument just this week in People v. Roth.

For another update on the Tulia debacle, read about the upcoming grievance trial against the prosecutor.