In United States v. Sokolow, the Court held that the Fourth Amendment does not preclude the use of "probabilistic" facts based on personal characteristics of a suspected drug courier as a basic for justifying a brief investigative detention. However, the Court did not clearly define the factors necessary to support a finding of reasonable suspicion, thereby leaving other courts with little guidance in future cases. In addition, the lack of a clear definition gives other courts seemingly unlimited discretion to intrude on citizens' Fourth Amendment rights by affirming determinations of reasonable suspicion. Moreover, the Court misinterpreted the earlier decision of Florida v. Royer, which expressly stated that a seizure must be sufficiently limited in scope and duration. Finally, the Court failed to recognize the significance and potential dangers associated with the use of drug courier profiles as a basis for determining reasonable suspicion. Such profiles have never been shown to be valid and have been proven to have no predictive value. Thus, the Sokolow ruling has major intrusive effects, despite its correctness regarding the facts of this specific case. 208 footnotes.