Illinois v. Caballes

Following is the case brief for Illinois v. Caballes, 543 U.S. 405 (2005)

Case Summary of Illinois v. Caballes:

  • A state trooper stopped Caballes for speeding.  Another trooper overheard the stop called over the radio.
  • The second trooper went to the location of the stop with a drug-detection dog and walked the dog around Caballes’ car, while the first trooper wrote Caballes a ticket.
  • The dog alerted to the trunk.  Inside the trunk, the troopers found marijuana.
  • Caballes unsuccessfully moved to suppress the marijuana at trial, and he was then convicted and sentenced to 12 years in prison with a hefty fine.
  • The Illinois Supreme Court reversed the denial of the motion to suppress.
  • The U.S. Supreme Court, however, reversed the Illinois Supreme Court.  It held that Caballes did not have a legitimate expectation of privacy in the drugs, therefore the dog sniff, which would only reveal illegal contraband, did not violate the Fourth Amendment.

Illinois v. Caballes Case Brief

Statement of the Facts:

An Illinois state trooper stopped Respondent Caballes on the highway.  The trooper then radioed to dispatch about the stop.  Overhearing the dispatch on the radio, an Illinois State Police Drug Interdiction Team headed to the stop with a drug-detection dog.  While the first trooper was writing out a warning ticket, officers from the Drug Interdiction Team walked the drug-detection dog around Respondent’s car.  The dog alerted to the trunk, and the troopers found marijuana.

Respondent was convicted of a drug offense and sentenced to a large fine and 12 years in prison.  Prior to trial, Respondent moved to suppress the drug evidence and quash his arrest.

Procedural History:

  • The trial court denied the motion to suppress, and the appellate court affirmed.
  • The Illinois Supreme Court, however, reversed. It found that the lack of “specific and articulable facts” regarding drug activity made use of the dog improper, by unjustifiably enlarging the scope of the traffic stop.
  • The U.S. Supreme Court granted certiorari.

Issue and Holding:

Does the Fourth Amendment require reasonable, articulable suspicion to justify use of a drug-detection dog during a routine traffic stop?  No.


The decision of the Illinois Supreme Court is vacated and remanded.

Rule of Law or Legal Principle Applied:

A dog sniff conducted during a routine traffic stop that does not prolong the stop, and only reveals the presence of an illegal substance does not violate the Fourth Amendment.


As a threshold matter, there was no prolonged, unlawful detention of Respondent in this case.  The duration of the stop was entirely justified by the traffic offense Respondent committed.  Further, there is no legitimate privacy interest in possessing contraband.  Therefore, the use of a drug-detection dog – which is only able to find the presence of contraband – does not infringe on any legitimate privacy interest.  Thus, there was no Fourth Amendment violation.

Concurring and Dissenting Opinions:

Dissenting Opinion (Souter):

Drug-detection dogs are not infallible.  In fact, they erroneously alert to items that prove not to be drugs many times.  A person’s privacy can be unjustly invaded by a drug-detection dog.  Therefore, using a dog in this case was a search unauthorized by the traffic stop, and unjustified on any other ground.

Dissenting Opinion (Ginsburg):

Under Terry v. Ohio, the Court focuses on the appropriate “scope” of a search.  Here, the dog sniff unreasonably expanded the scope of the traffic stop because there was no justification for any search beyond what was necessary based on Respondent’s violation for speeding.


Illinois v. Caballes is significant because it allows a drug-sniffing dog to be used during a routine traffic stop without implicating the Fourth Amendment.  Thus, even though there is no suspicion of wrongdoing with regard to narcotics, a dog sniff is permitted.

Student Resources:

Read the Full Court Opinion

Listen to the Oral Arguments