Near the end, they talk about how police can use psychological pressure to keep someone at the side of the road, not telling them they can leave any time the initial traffic stop is over. They then make 'productive' use of that time. Why you should never talk to police: http://www.youtube.com/watch?v=6wXkI4t7nuc
Judging from the 5 or 6 cops I know personally (neighbors and what not), there's basically nothing you can do if they want something from you. They will lie or provoke you into doing something, even worse, one of the cops I know had a story about how someone said, "no, you cannot search my vehicle." The cop then asked if he wanted to be arrested for resisting arrest, and the guy gave in because he has no idea what hi…
I would love to see a law on the books that forbids law enforcement officers from lying to witnesses or the accused to extract evidence or confessions. After all, it's unlawful to lie to them; the playing field should be level on both ends.