Authoritative digest of landmark Illinois and U.S. Supreme Court Fourth Amendment precedent governing roadside traffic stops, canine sniffs, stop duration limits, and officer safety authority.
The constitutional touchstones that govern every police roadside encounter in Illinois.
The constitutional reasonableness of a traffic stop does not depend on the actual subjective motivations of the individual officers involved. An observed traffic infraction justifies an initial stop regardless of pretext.
Officers may order the driver of a lawfully stopped vehicle to exit the vehicle as a matter of course without needing any particularized suspicion of danger (extended to passengers in Maryland v. Wilson).
A police stop exceeding the time needed to handle the matter for which the stop was made violates the Fourth Amendment. A stop cannot be prolonged for an unrelated dog sniff without reasonable suspicion.