Probable Cause and the Sniff Factor

Introduction

It is estimated that the close association between man and dog began in Europe over 12,000 years ago (Sloane, 1955). Man has used dogs to assist in hunting and guarding livestock for years. For centuries, man has used dogs in theaters of war dating back to early Egyptian times. The Romans used dogs to harass the enemy, as sentries, and they were used as pack animals to carry supplies. During World War II (WWII), dogs were used by the U.S. military for sentry duty, messenger work, locating injured soldiers, for attacking the enemy, and as pack animals. The “Dogs for Defense” organization was established in 1942 after the bombing of Pearl Harbor and throughout WWII, and the role of the dog expanded beyond sentry and messenger, to scout, to search and rescue, to assist locating the enemy, and to reduce the number of casualties (Sloane, 1955). In every theater of war since the Korean War, the U.S. military has trained and used dogs for varying purposes and since September 11, 2001, canines have been instrumental in sniffing out bombs and explosives, working with special operations teams, serving as a guardian for the troops, assisting in performing reconnaissance with patrols, and used as a form of deterrence in Afghanistan and Iraq (CBS, 60 Minutes, 2013a).

Because of their extremely acute sense of smell and hearing, the use of dogs in police work was a natural outgrowth from the military. The use of bloodhounds in the United States dates back to the 1840s when they were used to track down criminals and slaves (Sloane, 1955). Since the 1950s and with their success in the military, many metropolitan law enforcement agencies have trained and implemented the use of canines in police work and their role has expanded beyond tracking and attacking criminal suspects to include crowd control, drug detection, detecting explosives, criminal investigations, search and rescue operations, search for human remains by cadaver dogs, accelerate detection in cases of arson, and for officer protection (CBS, 60 Minutes, 2013b).

As criminals have become more sophisticated in concealing and disguising drugs, the use of dogs by the police has increased over the years. The United States Police Canine Association (2013) reports that over 7,000 police canine teams operate in North America. It is highly common today to see the words “K-9 Officer” on the side of a patrol car and to observe dogs working at airports, bus and railroad stations, sporting events, and other locations requiring a police presence. Dogs alert to many smells at a threshold well below that of humans. The research on the olfactory capacity of canines shows that some dogs can detect odors when the particles in the air are at a concentration of 500 parts per trillion (Johnston, 1999).

A well-trained dog with a highly trained handler can assist in locating illegal concealed drugs during a search on a traffic stop, search at school, residence, building, or other location requiring a search. A drug-sniffing dog is successful in locating drugs with high frequency and aids law enforcement in performing a search and judges have upheld the use of canines in performing searches (Taslitz, 1990). Dogs undergo numerous hours of training and are trained to alert to the presence of a particle of a substance and may alert to a large quantity or even to residual trace amounts making them highly reliable. Even with their high degree of sensitivity, a drug detection dog is not a gas chromatograph mass spectrometer and may alert even when drugs are not present (Myers, 2006). This problem could occur when a vehicle is suspected of containing drugs but does not, as the vehicle was previously used to transport drugs even if there are no drugs contained in the vehicle. Further, a handler assuming that drugs are present may prompt the dog to alert in order to justify the search.

Using a trained dog to perform a search can invoke a constitutional question of its reasonable legitimacy and has been previously challenged by criminal defendants on the premise that the officer lacked probable cause. The U.S. Supreme Court has repeatedly held that a sniff by a trained drug detection dog is not a Fourth Amendment search ( City of Indianapolis v. Edmond, 2000; Illinois v. Caballes, 2005; United States v. Place, 1983). Although these decisions addressed the issue of probable cause and searches with the use of canines, the Court granted certiorari to review two additional cases which involve the use of a drug detection dog while performing a search in its 2012–2013 term. In Florida v. Harris (2013), the Court examined the issue of whether a court should determine if the alert of a drug detection dog during a traffic stop provides probable cause to search a vehicle. Further, in Florida v. Jardines (2013), the Court reviewed the issue of whether using a drug-sniffing dog on a homeowner’s porch to investigate the contents of the home constitutes a search within the meaning of the Fourth Amendment.

Since its establishment in 1789, the Court has ruled on the issue of performing searches with the use of canines on three occasions, yet in one term the justices reviewed two cases on the subject underscoring the importance of their use. The war on drugs has used various strategies to combat the problem, including the use of dogs. Trained drug detection dogs are an effective law enforcement tool because of their superior ability to detect the odor of contraband. This article presents a review of the Court’s decision in Harris and Jardines, an assessment of the distinctions between the decisions, and presents a discussion on the implications of these holdings.

Prior U.S. Supreme Court Decisions and the Use of Canines

The Fourth Amendment states that “the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.” In Illinois v. Gates (1983) and affirmed in Messerchmidt v. Millender (2012), the Court ruled that probable cause to search exists when there is a fair probability that contraband or evidence of a crime will be found in a particular place. The standard does not require the same degree of certainty that is required to determine proof of guilt or the preponderance of evidence ( Maryland v. Pringle, 2003). Probable cause to search is frequently based on an officer’s sensory observations, including a sense of smell ( United States v. Johns, 1985). This is allowed as distinctive odors emanating from a particular location makes it fairly probable that the substance producing it is present.

The odor of drugs at a location provides a fair probability to search that location for drugs or evidence of drug crimes. Each drug has a scent signature that includes a combination of molecules that the dog is trained to recognize (Bryson, 2000; Taslitz, 1990). A dog’s keen sense of smell is superior to a human and permits it to detect faint odors that are undetectable to humans and provides an even stronger basis for probable cause to search the area for the odor’s source. The heightened sense of smell makes a dog an important tool to law enforcement as the dog can alert to drugs well hidden or can detect the odor of drugs masked by other scents. When the dog indicates that the odor of drugs is present at particular location, there is probable cause to search. The dog is trained to recognize drug scent and in terms of the chemistry of the drug, a dog alerts to the scent. Hence, a trained dog that alerts is indicating that the odor shows presence of a drug, which underscores a fair probability. Probable cause is not based on certainty and only a fair probability need exist to justify the search. The mere possibility that a dog’s alert may have been to residual odor of drugs no longer present is irrelevant. Drug residue by itself is indeed evidence of a crime ( State v. Foster, 2011; United States v. Ludwig, 2011).

In three previous decisions, the Court has examined the issue of establishing probable cause based on the smell and alert of a drug detection dog and determined in each case that a sniff by a trained drug detection dog is not a Fourth Amendment search. In United States v. Place (1983), the Court held that a canine sniff of luggage at an airport was reasonable and is an important investigative technique because it does not require opening the luggage. Raymond Place raised the suspicion of drug enforcement agents (Drug Enforcement Administration [DEA]) at the Miami airport and they briefly detained him for questioning. He agreed to a search of his luggage but because his plane was departing within minutes, the search was postponed. The DEA agents called ahead to agents in New York City and they stopped Place when he exited the plane. The agents suspected that Place was carrying narcotics but he would not consent to a search of his luggage. The agents detained Place, transferred his luggage to the Kennedy Airport, and informed him that he could retrieve them there. A trained drug detection dog sniffed the closed luggage and alerted, indicating the presence of drugs. Because the incident occurred on a Friday, the bags were held unto Monday, when a search warrant was obtained. Upon the search, drugs were found in the bags.

The Court held that the length of the detainment of Place violated the brevity requirement under a Terry stop, but the manner of the search was reasonable, as the agents used a trained canine to sniff the luggage and it did not require them to open the luggage. The agents did not open the bags and rummage through the contents. The Court held that using a trained drug detection dog to perform a sniff is a less intrusive technique than a general search performed by a law enforcement officer. Thus, if the sniff performed by a dog indicates the presence of drugs or other contraband, the possessor has no protected constitutional right. The Court held that a dog sniff of luggage at an airport was not a search because it is much less intrusive than a normal search and characterized the dog sniff as “sui generis” (a special category). The Court opined that a dog sniff is a unique type of investigatory technique as it is limited in the manner in which the information is obtained and in the content of the information revealed by the procedure. The Court’s ruling allows the police to use a trained drug detection dog to confirm the presence of drugs when they have reasonable suspicion that a person may possess drugs.

In City of Indianapolis v. Edmond (2000), the Court ruled that using a trained drug detection dog did not transform the seizure into a search. The Indianapolis police began a vehicle checkpoint program to detect for illegal drugs. The checks occurred during the day, were planned in advanced, and were clearly marked by signs. Vehicles were randomly stopped and as the officer checked for signs of impairment and conducted a plain view observation of the vehicle, while another officer walked around the vehicle with a drug detection dog. Only if the officer developed particularized suspicion of illegality was the driver detained and further investigation conducted. Edmund and others were stopped at the checkpoints and challenged the constitutionality of the stops.

The Court held under the Fourth Amendment, the general rule is that searches and seizures are unreasonable unless there is individualized suspicion of criminal wrongdoing and in roadblocks there is no individualized suspicion of wrongdoing. There are however, three exceptions: (1) roadblocks that secure the border; (2) for the purpose of apprehending drunken drivers, and (3) when the purpose is to verify a driver’s license and registration. The Court rejected the premise to allow a fourth exception to perform stops to control the flow of drugs in the community as it was too general in scope and setting up roadblocks for this purpose was unjustified.

The Court emphasized that it is well established that a vehicle stop at a highway checkpoint effectuates a seizure within the meaning of the Fourth Amendment. Referencing their decision in Place, the Court ruled the fact that an officer walked a narcotics detection dog around the exterior of each car at the checkpoints did not transform the seizure into a search. Just as in Place, an exterior sniff of an automobile does not require entry into the car and is not designed to disclose any information other than the presence or absence of narcotics. Like the dog sniff in Place, a sniff by a dog that simply walks around a car is “much less intrusive than a typical search.” Thus, while Court held that the purpose of the stop program was unconstitutional, the justices ruled that using a trained drug detection dog to walk around a vehicle to sniff for drugs did not violate the constitution, as it does not involve intrusion into private or intimate areas by a dog or his handler.

In Illinois v. Caballes (2005), the Court ruled that using a drug detection dog to sniff a vehicle during a traffic stop did not violate the Fourth Amendment. An Illinois State Police Trooper stopped Roy Caballes for speeding, radioed dispatch, and a second trooper responded pursuant to policy, and walked his narcotics dog around Caballes’ vehicle. The dog alerted and the troopers searched the trunk of the vehicle and found marijuana. Caballes was arrested, prosecuted, convicted, and sentenced to a 12-year prison sentence and assessed a US$256,136 fine. Caballes appealed based on a lack of probable cause to conduct the search and the Illinois Supreme Court agreed, holding that there must be some basis for turning a speeding violation into a narcotics investigation.

The U.S. Supreme Court reviewed the case and rejected the Illinois Supreme Court’s conclusion that reasonable suspicion was a necessary predicate for a lawful dog sniff. The Court focused on the issue of whether deployment of a trained dog constituted a search under the Fourth Amendment violating the right to privacy. The Court noted their previous decision in Place affirming that dog sniffs are “sui generis” and reaffirmed that a sniff does not compromise any legitimate interest in privacy and is not a search. The Court opined that Caballes was lawfully stopped for speeding, was being issued a warning ticket, while a second trooper walked the trained narcotics dog around the vehicle. The dog alerted and marijuana was found during the subsequent search. The Court held that walking a drug dog around a vehicle would not change the character of a traffic stop that is lawful at its inception and otherwise was executed in a reasonable manner. The Court further added that no privacy interest was violated because the dog sniff was performed on the exterior of the vehicle, while Caballes was lawfully seized for a traffic violation. Any intrusion on Caballes’ privacy expectation does not rise to a level of constitutionally cognizable infringement and does not violate the Fourth Amendment.

In Caballes, the Court relied on the contraband exception to what constitutes a search that was established in United States v. Jacobsen (1984). Under this exception, any test, including a dog sniff, which merely reveals contraband, and no other private fact, compromises no legitimate privacy interest, and is not a search. The Jacobsen exception underscores the principle that an individual has no legitimate interest in possessing contraband and it is the method of finding the contraband that the Court is exempting. Based on their training, drug detection dogs are trained to detect odors emanating from a location and when the dog alerts, he conveys only the public fact that the location contains drugs. Thus, the rule established in Caballes is that the Fourth Amendment does not regulate dog sniffs.

Two Dog Sniff Cases

Like past case decisions of the Court, additional constitutional questions emerge over time which challenge an original case decision or which presents new questions or challenges to the decision. As drug detection dogs continue to be used in the fight against crime and the war on drugs, new legal challenges have surfaced. In its 2012–2013 term, the Court again examined the issue of using canines and probable cause. The first decision in Harris examined probable cause to search a vehicle with a canine during a traffic stop, while the second decision in Jardines examined whether a search was convened by a drug detection dog on the porch of a residence who alerted to odors of narcotics coming from the residence.

Implications

The Court’s focus of these two cases is directed at the appropriate use of trained dogs in varying situations and at the thrust of these decisions is the issue of probable cause formation for the purpose of performing a lawful search. Jointly, the Court’s decisions in both cases are instructive on several levels. First, they provide reminders of what constitutes an objectively reasonable search in accordance with the Fourth Amendment. Citizens are protected from “unreasonable searches and seizures.” Second, the case decisions provide an analysis that an objective reasonable search is premised on establishing probable cause. As a legal standard, probable cause is different than proof beyond a reasonable doubt or preponderance of evidence, which are finely tune standards used in formal trials. Probable cause does not require the degree of certainty that would be required to establish proof of guilt or even to establish a fact by a preponderance of evidence. Third, the Court emphasizes that probable cause to search is a fluid concept not readily or even usefully confined to a neat set of rules and exists when there is a fair probability that contraband or evidence of a crime will be found in a particular place. Hence, probable cause as a flexible standard is assessed by an officer acting upon the facts available, based on a fair probability, and further examined within the “totality of circumstances.” Probable cause deals with probabilities and not absolute certitude, even when law enforcement officers use a trained dog.

In Jardines, the Court took occasion to provide a brief historical review of the importance of protecting a citizen’s home from an unreasonable search in accordance with the Fourth Amendment. In accordance with the Fourth Amendment, a citizen’s home is first among equals, requiring a high degree of protection from unreasonable searches and seizures and where privacy expectations are most heightened. A residence is considered property and it is a person’s most intimate and familiar space. In emphasizing the importance of protecting the home, the Court reached back to English common law commenting that the “curtilage and homestall,” is protected. This is interpreted to mean the home itself, the areas around the home, including those areas that are linked “physically and psychologically.” The included “areas” of the home can be said to include adjacent areas which extend activities of the home. This would generally include porches, sheds, walkways, breezeways, patios, driveways, garages, and other property. The property rights of citizens (the home) are sacred and no one may enter the premises without permission. Citing their decision in Silverman v. United States (1961), the Court underscored the key component of the Fourth Amendment stating that at the amendment’s core is the right of a man to retreat into his own home and there be free from unreasonable governmental intrusions. The Court emphasized that the home and the surrounding area are constitutionally protected requiring authorization prior to performing a search.

The historical background of protecting the home from unauthorized governmental intrusion is important to understanding the Court’s decision. The law of property naturally influences society’s shared expectations of what places should be protected from governmental intrusion. The Court emphasized a distinction between a person’s automobile and their home, stating that the level of privacy is much lower in a car. In this case, the Court determined that the officers crossed a “firm line” by intruding onto the protected premises of the home for the purpose of conducting an investigation and search without a warrant.

The implications of the Court’s decision go beyond the narrow question of whether a law enforcement officer may bring a trained drug detection dog onto the curtilage (porch) of the residence but rather focused on what a home owner would allow anyone to do who approaches their front door. In addressing this concern, the Court directed the attention of law enforcement to consider the issue of trespass and what their intent and purpose is when they enter the protected premises of a home. The issue facing law enforcement is to determine what their purpose is for entering the protected area of the home. In this incident, the officers’ behavior objectively showed their purpose was to conduct a search, which was not what anyone would think they had license to do. The officers were not invited to the home, they did not respond to the home based on exigent circumstances, nor were they armed with a search warrant, which would have provided authorization to be there. The officers approached the home to perform an investigation and used a trained dog to sniff for drugs in order to complete the investigation. Since none of these conditions applied and the purpose was to perform an investigation, and the officers performed an investigation on a protected area while using dog, which constituted a search, an illegal search occurred. It did not matter that the officers remained outside of the residence. The officers performed an illegal search without a search warrant using the dog to sniff the constitutionally protected area of the home.

Based on this decision, law enforcement officers must consider what their purpose of entering the premises of the home are. If the officer is entering the premises of the home for a purpose beyond knocking at the door to ask a question, to provide information, or to make a delivery, the trespass analysis will most likely apply and any evidence discovered as a result would most likely be inadmissible (Ryan, 2013). When an officer desires to conduct an investigation of the home, a search warrant is required by the Court, regardless of the techniques or resources used, including that of a canine.

In the Harris decision, the Court further addressed the issue of probable cause and an officer basing a search on the alert of a trained drug-sniffing dog. The probable cause component of fair probability was further examined. The Harris decision impacts the importance of assuring that the officer and the dog have received the appropriate training. Harris attempted to argue that the reliability of a trained drug-sniffing dog should be measured by the dog’s performance in the field, through assessing the record of hits and misses, and such performance should be considered when determining whether probable cause existed. The Court rejected this standard.

The Court’s decision in Harris has important training implications. The Court determined that field data may not accurately capture a dog’s performance, as it may overstate or understate the hits or misses. The Court held that a better measure of a dog’s reliability comes from a controlled testing environment. Evidence of a dog’s satisfactory performance comes from the training and certification program which provides sufficient reason to trust the dog’s alert. Probable cause to search then comes from the training and certification process of a bona fide training program that the dog completes which is the important factor for determining the dog’s reliability, not field performance.

This decision is in deference to law enforcement and the Court acknowledged that they have a strong interest in ensuring that the training of dogs will accurately perform their assigned role without wasting time and valuable resources. Thus, the implications of this decision should reaffirm and motivate law enforcement agencies to continue to provide dog handlers and their selected dogs with training from a bona fide certification program. Training programs that rely on principles that a dog can be trained to respond consistently to certain sensory stimuli which alert the handler should be used. Training programs that train and test a dog in a controlled environment (as discussed by the Court) provide the only effective means of determining whether a dog has undergone the requisite training which produces the reliability of the dog to alert to the stimuli or odor. Training programs that design evaluation exercises for contraband detection dogs should be used by law enforcement agencies. Using such exercises the instructor knows the location of where the contraband is hidden and the dog and the handler do not. These exercises also prevent the handler from inadvertently cuing their dog. Thus, by correlating a dog’s alerts and nonalerts to those known locations, the true reliability of detecting drug odors can accurately be assessed. A dog’s record in a controlled certification and training setting is the best method for ensuring the reliability of the alert. Successfully completing these types of training and certification programs comports with the Court’s ruling in Harris. When a dog alerts in accordance with its training, a court should find the alerts reliable and was appropriate to establish probable cause justifying the search.

Law enforcement agencies should also provide ongoing training past the initial training for their dog handlers and their dogs and ensure that they fully document and retain all of the training records. Maintaining a commitment to providing ongoing training can enhance the dog’s and the handler’s performance in the field and comports with the Court’s ruling in City of Canton v. Harris (1989) which held that law enforcement personnel must be provided with ongoing training commensurate with their assigned duties.

A dog’s credentials as well as the handler’s provide a highly important component for determining the reliability of the dog’s alerts. Documenting and explaining these credentials will demonstrate to a court what is exactly required in endorsing support for a Fourth Amendment probable cause search. While no dog is infallible, that dog which was trained and certified to alert to specific stimuli and odors, and accordingly alerts in the field, demonstrates a “fair probability” sufficient to establish probable cause warranting a search consistent with the Court’s ruling.