In Indianapolis v. Edmond, 531 U.S. 32 (2000), this Court held that the police may not employ highway checkpoints to search for drugs. This case involves a related question: whether the police may expand a routine traffic stop into a drug investigation by using a drug-sniffing dog in the absence of individualized suspicion.. The ACLU argues that the presence of dogs fundamentally alters the nature of the seizure and therefore requires independent and constitutionally adequate justification.