The Court did rule, however, that detaining a person's belongings while waiting for a police dog to arrive did constitute a "seizure" under the Fourth Amendment.

[2] In Illinois v. Caballes (2005), the Court held that it did not violate the Fourth Amendment to use a drug-detection dog during a legal traffic stop, as long as it did not unreasonably prolong the duration of it.

The detectives notified Drug Enforcement Administration agents at LaGuardia Airport to Place's suspicious activity, alerting them of his arrival.

About 90 minutes later, Place's luggage was subject to a "sniff test" by a trained drug-sniffing police dog, who alerted to the presence of illegal narcotics at one of the suitcases.

[7] As the luggage was detained on a Friday, agents kept the suitcases in police custody until a search warrant could be issued by a federal judge the following Monday, on August 20.

[5] When tried in the district court, Place moved to suppress the cocaine, arguing that the warrantless seizure of his luggage violated his Fourth Amendment rights.

[8] The district court disagreed, holding that the police having reasonable suspicion that the luggage contained narcotics justified the detention of his belongings, and exposing it to a trained drug-sniffing dog was an acceptable escalation of their investigation.

[11] The Fourth Amendment protects the interest people have in keeping their persons, houses, papers, and effects free from unreasonable searches and seizures.

Indeed, when government agents have reason to suspect (but not probable cause to believe) that, for instance, a traveler's luggage contains narcotics, it has a substantial interest in confirming or denying that suspicion.

Justice Brennan concurred in the Court's judgment because he agreed with the Second Circuit that the scope of the agents' seizure of Place's luggage was unreasonable.