fourth amendment's prohibition against unreasonable seizures. the experts say finding the initial reason to pull someone over is easy. >> there is 500 aspects of the traffic code in north carolina between the traffic code and vehicle code. >> it's not just north carolina that became apparent during an afternoon with an officer of the oakland, california police department. >> this infinity has a bumper loose. that's a vehicle violation. top brake light does not work. i can stop him for that. >> there are 18,000 police departments across the u.s., and no standards for which violators to pull over. >> are you still trained at traffic stops are one of the most dangerous things that can happen. >> you definitely are. you may stop somebody for what you believe is the typical broken taillight. and you don't know they just shot somebody. you have to remember that there is guns in the streets.