In many cases, the issue of whether or not there has been an impermissible acquisition of evidence will involve two different questions: (1) was there an illegal seizure of the suspect (detention or arrest) leading to discovery of the evidence, and (2) was there an unlawful search of the suspect or his property during which the evidence was found?
In the usual case, both the seizure and the search must be reasonable under the Fourth Amendment in order for the evidence to be admissible. The U.S. Supreme Court and federal appeals courts have considered both issues when officers have used K-9s to detect contraband.
The "Seizure" Issue
If you make an unjustified detention or arrest in order to get an opportunity to search, any evidence you then find will generally be "tainted" by the fact that it resulted from an unreasonable seizure. (Florida v. Royer) In most cases, a detention must be based on reasonable suspicion that the individual is involved in criminal activity (Terry v. Ohio).
An exception to this rule allows suspicionless stops at certain checkpoints that the court has said do not violate the Fourth Amendment. To date, these have been limited to vehicular checkpoints to make brief inspections for immigration compliance (U.S. v. Martinez-Fuerte), driver's license and registration (Delaware v. Prouse), driving under the influence (Michigan v. Sitz), and witnesses to recent serious crimes. (Illinois v. Lidster) Based on these exceptions, the City of Indianapolis decided to establish vehicular checkpoints to check for narcotics.
Under the Indianapolis procedure, police set up lighted roadway signs warning motorists "Narcotics Checkpoint 1 Mile Ahead. Narcotics K-9 in Use. Be Prepared To Stop." At the checkpoint, a predetermined number of vehicles would be detained only long enough to run a dog around the car and ask a few questions, while other traffic proceeded without interruption. The "hit" rate on the stopped vehicles was a fairly high 9 percent.
Two motorists who had been stopped at the drug checkpoint sued the City of Indianapolis and its police department, claiming a violation of their Fourth Amendment right against unreasonable seizure. The Supreme Court agreed that the checkpoint violated the Fourth Amendment and allowed the suit to proceed.
The court pointed out that other kinds of checkpoints it had approved had some primary purpose other than detection of criminal activity (border control, highway safety, or locating witnesses). None of them had the essential purpose of crime detection. This distinction made the checkpoint detentions in Indianapolis different, and unreasonable.
The court said this:
"It is well established that a vehicle stop at a highway checkpoint effectuates a seizure within the meaning of the Fourth Amendment. What principally distinguishes the Indianapolis drug-detection checkpoints from those we have previously approved is their primary purpose-interdicting illegal narcotics.
"We have never approved a checkpoint program whose primary purpose was to detect evidence of ordinary criminal wrongdoing. Rather, our checkpoint cases have recognized only limited exceptions to the general rule that a seizure must be accompanied by some measure of individualized suspicion. Because the primary purpose of the Indianapolis narcotics checkpoint program is to uncover evidence of ordinary criminal wrongdoing, the program contravenes the Fourth Amendment" (Indianapolis v. Edmond).[PAGEBREAK]
Although the court invalidated use of a checkpoint to run a drug-sniffing K-9, the court's opinion was careful to limit its holding to "ordinary" criminal wrongdoing. The court added, "The Fourth Amendment would almost certainly permit an appropriately tailored roadblock set up to thwart an imminent terrorist attack or to catch a dangerous criminal who is likely to flee by way of a particular route."
The "Search" Issue
Assuming the lawfulness of a detention(stop is based on a reasonable suspicion of criminal activity), merely running the K-9 around the vehicle or container does not constitute a Fourth Amendment "search," and need not be independently justified. Even while invalidating the Indianapolis drug checkpoint in the Edmond case based on the illegal seizure, the court noted that the K-9 sniff was not itself a search: "The fact that officers walk a narcotics detection dog around the exterior of each car does not transform the seizure into a search." (Indianapolis v. Edmond)
In U.S. v. Place, DEA agents at a New York airport, acting on information from officials at the Miami airport, seized Raymond Place's luggage and held it for 90 minutes before a K-9 was brought to sniff it. After the dog alerted, agents opened the luggage and discovered a large quantity of cocaine. The Supreme Court suppressed the cocaine as evidence because it held that the 90-minute detention of the luggage was too long, but the court noted that the dog sniff did not constitute a search:
"The sniff discloses only the presence or absence of narcotics, a contraband item. Therefore, we conclude that the particular course of investigation that the agents intended to pursue here-exposure of respondent's luggage, which was located in a public place, to a trained canine-did not constitute a 'search' within the meaning of the Fourth Amendment" (U.S. v. Place).
In Illinois v. Caballes, a state trooper stopped a car for speeding. During the time it would normally take to issue a traffic warning or citation, another officer arrived with a K-9, ran it around the car, and searched the trunk after the dog alerted there. Driver Caballes moved to suppress the marijuana found in his trunk, but the Supreme Court denied the motion. Since in this case the seizure of the suspect was justified by the traffic violation, and since a K-9 sniff is not a search, there were no grounds for suppression.
Said the court:
"Official conduct that does not compromise any legitimate interest in privacy is not a search subject to the Fourth Amendment. We have held that any interest in possessing contraband cannot be deemed 'legitimate,' and thus any governmental conduct that only reveals the possession of contraband compromises no legitimate privacy interest. The trial judge found that the dog sniff was sufficiently reliable to establish probable cause to conduct a full-blown search of the trunk. Accordingly, the use of a well-trained narcotics detection dog during a lawful traffic stop does not implicate legitimate privacy interests" (Illinois v. Caballes).
Combining Legal Principles
In Whren v. U.S. and Arkansas v. Sullivan, the Supreme Court ruled that a lawful traffic stop could be used to provide the opportunity for a brief narcotics investigation. In Caballes, the court said that a K-9 could be run during a valid traffic stop. This means that if you have a K-9 ready, you may stop suspected drug offenders for moving or equipment violations and run the dog while you discuss the traffic violation. If the dog hits, you have PC to search and arrest.
Federal appeals courts have approved of such tactics as setting up narcotics checkpoint signs (without any actual checkpoint) and stopping cars when they commit traffic violations while trying to avoid the advertised checkpoint. The traffic stop is permissible under Whren, and a K-9 sniff within the scope of such stops is permissible under Caballes (U.S. v. Wright — stop sign violation; U.S. v. Adler — improper signal).