Should you be arrested for anything in your vehicle the first thing your lawyer should do is challenge the circumstances under which your car was searched. He can't do that if you gave up your 4th amendment protections.
There are ways they can get around the 4th amendment. One is a dog. Let's say you pull up to a "safety check point" and the police have dog running around the cars. This is legal and has been held up in court as not violating your privacy rights. If they ask to put the dog in the car you can refuse. Hypothetically, if in a case like this one they used a dope sniffing dog, said he alerted, searched the car, found no drugs and then came up with the magazines then I expect a defense attorney would challenge the dog and the results of the search.
There are some police who are really good (like Obi Wan Kenobi good) at getting people to give consent to search. A good friend of mine popped a couple guys carrying 100 lbs. of cocaine, that gave him consent to search off a simple traffic stop. He knew they had the drugs, but when he asked politely there was something about the way he asked that kept them from saying no.
It comes to me that the politicians henchmen don't much mind violating the citizens rights as long as they themselves are exempt from such laws..
I think we now know why the politicians are exempting the police from the ridiculous laws that violate our rights under the constitution...