>> i think that the simple rule if i may propose one is the same one that professor lafave has per proposed. the officer sees the infraction. the officer pulls the person over. the officer tells the person what the infraction is. he does the license, registration, runs the car. when that is done, he gives them the ticket, the warning ticket. that is end of the traffic stop. there's no other reason to hold the person after that point in time. >> you say he runs the car, he puts the license plate into the radio and waits from the report from the station as to whether or not the license is okay. >> yes, your honor. >> why is that part of the mission and the dog sniff is not. that's the question. if you're not going to have a formal rule, you have to explain why somebody is pulled over for a broken tail light, why adding any time to the stop in order to do a records check is part of the mission but the dog sniff is not. i could understand the rule. you pull somebody over for a broken tail light. may be you get the registration and maybe sure you write out the ticket to the right person and then