Your refusal to consent does not in any way provide probable cause, or reasonable suspicion, to an officer. It might give the officer a hunch about what you are doing, but hunches aren't admissible in court! Having said that, depending on the circumstances of any given contact, you may find that an officer asks for consent, gets the consent denied, but still performs a legal search. By way of example, if I stop a driver of a vehicle who has a suspended license, I have the ability to impound that car (and often do impound that car). Having made the decision to impound that car, I am now obligated to conduct an "inventory search" of that vehicle prior to placing it in our impound lot. But, I also like to cover all my bases, so I'll often ALSO ask for consent before I search the car (even though I can legally search the car, and will do so before it is towed). Personally, I see this question come up a lot, but I doubt it is anything that most of us will ever need to confront. I will rarely ask for consent if I don't have a real good hunch that I will probably find something illegal. Moreover, many years ago (long before I was a cop) I was a kid with quite the lead foot. I got pulled over quite a few times, and ended up with a few tickets along the way. I was never asked even once to have my vehicle searched in all of these stops. I'm not saying that it can't happen, but I don't think it is a real problem that most people will need to deal with.