The subject of this Article is an exceedingly important one, as is reflected by the fact that in recent years more Fourth Amendment battles have been fought about police activities incident to what the courts call a "routine traffic stop" n7 than in any other context. There is a reason why this is so, and it is not that police have taken an intense interest in such matters as burned-out taillights and unsignaled lane changes per se. Rather, as anyone not on a trip to Mars over the past decade or so is surely aware, the renewed interest of the police in traffic enforcement is attributable to a federally sponsored initiative related to the "war on drugs." n8 Both in urban areas and on the [*1845] interstates, police are on the watch for "suspicious" travelers, and when a modicum of supposedly suspicious circumstances are observed - or, perhaps, even on a hunch or pursuant to such arbitrary considerations as the color of the driver's skin n9 - it is only a matter of time before some technical or trivial offense produces the necessary excuse for a traffic stop. n10 Perhaps because the offenses are often so insignificant, n11 the driver may be told at the outset that he will merely be given a warning. But then things get ugly. As a part of the "routine," a criminal-history and outstanding-warrants records check is run on the driver and passengers; they are closely questioned about their identities, the reason for their travels, their intended destinations, and the like, and may be quizzed as to whether they have drugs on their persons or in the vehicle. The driver may be induced to submit to a full search of the vehicle, or a drug-sniffing dog may appear on the scene and "do his thing."

[*1846] My favorite illustration of this tactic is United States v. Roberson. n12 A Texas state trooper on patrol at night passed a van and noted it had out-of-state plates and four black occupants, so he pulled off onto the shoulder after cresting a hill, turned his lights off, and then observed the van change lanes to provide more distance between it and the vehicle parked on the shoulder. The lane change was unaccompanied by a signal, which hardly seems remarkable in view of the fact that the van was "the only moving vehicle on that stretch of road," but the trooper "obviously regarded this as a serious traffic offense," for he pulled the van over. n13 He then questioned the van's occupants on unrelated matters and finally exacted consent to search the vehicle, which resulted in the discovery of drugs. Despite the court's familiarity with this trooper's "propensity for patroling the fourth amendment's outer frontier" and his "remarkable record" of turning traffic stops into drug arrests on 250 prior occasions, the defendants in Roberson were deemed to be without any basis to challenge the stop because, after all, the trooper had "observed a traffic infraction before stopping the vehicle"! n14

Cases of this genre raise a number of important issues concerning the Fourth Amendment legalities of the "routine traffic stop" from start to finish. As to the start, there are various questions concerning the limitations upon when such a stop may be initiated. As to the finish, there are questions concerning what is necessary to constitute a termination of custody and what official actions thereafter will or will not constitute a new seizure. And then there is the in-between, that critical period between start and finish; as to it, there is another set of questions concerning how long the seizure may continue and what investigative techniques and tactics are permissible during that interval.