http://boingboing.net/2008/07/28/law-prof-and-cop-agr.html
The risk of self-incrimination is incredibly high since no person can even be aware of all of the laws that exist and may be violated.
It takes a certain amount of cahones, but you'll generally find that the cops will respect it.
A pricey court appearance beats a conviction in my book.
http://www.thisamericanlife.org/radio-archives/episode/430/v...
Exited the car, locking it. Identified myself and presented ID. Refused consent to search the vehicle: "I don't consent to any search". Officer implied strongly that he could get a warrant (it's around midnight). "You do what you've got to do, I don't consent to a search".
Got breathalyzed (I could have refused this but that would have required a trip for a blood draw), which was clean (hadn't consumed any alcohol for hours). Eventually allowed to go on my way.
Later realized I had a couple of prescription painkiller pills given by a friend (for severe pain I was experiencing at the time) which probably wouldn't have been a good thing to turn up in a search. The This American Life drug court segment relates a story that could have been very similar to mine.
You have rights. But only if you assert them.
Note that when I did assert my rights, I really didn't have any reason for doing so other than that they are my rights. It was literally a couple of years later that I made the association between the stop and the possibility that I may have been carrying what were technically illegal drugs.