This is a must see for anyone that walks, drives or breaths--especially if you carry a weapon for self-defense. This includes not only a short presentation by the law professor, James Duane, but a guest presentation from a police officer discussing how he goes about questioning suspects. Also read the The Truth About Knives article (linked to below).
The short take is that police are not going to play fair in questioning, especially if they feel that you have broken a law. For example, around here, if you get pulled over for speeding, the first question is a damned-if-you-do-damned-if-you-don't type: "How fast were you going?" If you say you don't know, then you have opened yourself up to a citation for inattentive driving. If you say that you though you were going "X" miles per hour (a few miles per hour over the speed limit), you had admitted to speeding.
And remember that everything you say to the police is an admission against interest, which is not considered hearsay. But everything the police say to you is probably going to be considered hearsay.
Anyway, watch the video and read the article. I'll try and have some more thoughts this weekend.
(H/t The Truth About Knives).