For nearly 15,000 years 1 dogs have lived with and served humankind as companions, hunters, shepherds and most recently detectives. 2 The average canine possesses hundreds of millions of receptors for odors, compared with a few million for humans. 3 Their outstanding sensory endowment, olfaction, makes dogs sought after by law enforcement. And in the last century, the cultivation and harnessing of this ultrasensitive faculty has become a part of many facets of criminal investigation.
Detection or sniffer dogs are used to ferret out illicit and dangerous substances, such as accelerants, explosives, illegal drugs, 4 environmental hazards 5 and other contraband. 6 While these service dogs' abilities are highly touted, the use of an animal's olfactory sense in ascertaining the cause of a fire 7 or locating drugs raises Fourth Amendment 8 , evidentiary and due process issues.
This article surveys select studies, standards and resources about canine scent detection evidence.
Canine Detection Capabilities: Operational Implications of Recent R & D Findings (Institute for Biological Detection Systems, Auburn University 1999)
"Dogs have been successfully used for many years by military and law enforcement agencies to detect varied substances. However, the science underlying their olfactory detection capabilities has been slow to accumulate and even slower to impact operational training and deployment protocols. Since 1989, the Institute for Biological Detection systems (IBDS) at Auburn University has worked to ameliorate this problem. A number of recent laboratory and field studies have begun to reveal the dog's olfactory sensitivity, how it recognizes substances, and how it performs in the field. This paper summarizes selected findings and their possible operational consequences."
Dog Scent Lineup as Scientific Evidence (International Academy of Forensic Sciences, August 1999, Los Angeles, CA)
"Ten years ago Taslitz (1990), in his comprehensive study on dog scent lineups, expressed a view that the uniqueness and stability of human odour had not been established yet and experimental research in the area of dog scent identification still was in its infancy, therefore scent lineups should be excluded from evidence in court. A decade in forensic science is more than a century in law, however, so it seems worthwhile to look at the possibilities of canine human scent identification again."
Scents and Sense-Ability, Forensic Magazine, April/May 2006
"Europeans have used scent-discriminating dogs to aid criminal investigations for over a century. Reputed to have a sense of smell 1,000 to 10,000 times more superior than that of humans, a dog's nose does offer a sensitive forensic instrument. Traditionally, dogs contributed to police work by stalking a suspect's track. During the latter part of the twentieth century, investigators found a new way to employ the canine's olfactory skills: perform a scent lineup to connect a person with a crime via scent evidence. Dogs trained for scent identification are 'specialist, biological devices,' according to Tomasz Bednarek, the Head of the Warsaw Metropolitan Forensic Laboratory and an expert on osomology – a system of human scent identification."
Specialized Use of Human Scent in Criminal Investigations, Forensic Science Communications, July 2004
"Using scent-discriminating dogs in criminal investigations should be limited to establishing a scent relationship between people and crime scene evidence. Because human scent is easily transferred from one person or object to another, it should not be used as primary evidence. However, when used in corroboration with other evidence, it has become a proven tool that can establish a connection to the crime."
Canines (NLADA Forensics Library)
The National Legal Aid and Defender Association maintains a collection of pleadings, expert testimony, research articles and opinions concerning the reliability of dog detection evidence.
Canine Detection Research Institute (Auburn University, College of Veterinary Medicine)
"TheAuburnUniversityprogram is the largest dedicated canine detection research program in the United Statesand its associated Canine Detection Training Center (CDTC) is one of the largest canine detection training programs outside of the federal government."
Canine Database (Florida Gulf Coast University)
"The Florida Gulf Coast University Canine Database is a clearinghouse of published research on police and work dogs. This database publishes research, technical reports, and data collected in other canine-related projects." See Articles by Topic and Research Links.
Canine Sniffs & Scent Detection (NCSTL)
This Hot Top section of the National Clearinghouse for Science, Technology & Law (NCSTL) contains a bibliography of materials from legal and forensic publication sources on dog scent evidence.
Service Dogs (UC Davis, Veterinary Medicine)
"This web site contains useful links to web sites, journal articles, and books that discuss service dogs. Service dogs are trained in very specific ways to help their human counterparts. Service dogs include police dogs, accelerant detection dogs, agriculture inspection dogs, war dogs, and psychiatric dogs."
"The United States Police Canine Association (USPCA) became the largest and oldest active organization of its kind-'Ever Striving for the Betterment of all Police K-9' - in August, 1971 when two existing Associations, the Police K-9 Association and the United States K-9 Association, merged." See Canine Training Articles.
IFRI/NFSTC Detector Dog Team Certification Program (International Forensic Research Institute)
"The program is intended to provide recommended scientific standards of practice for trainers and organizations and to make available an additional layer of credentials for detection teams. The ongoing goal of this program is to continue to advance scientifically sound detection K-9 validation programs which are internationally recognized and which improve contraband interdiction from local enforcement to courtroom defensibility."
National Detector Dog Manual (USDA 2003)
"The National Detector Dog Manual covers background information, procedures, health care, and training related to detector dog activities. The procedures have a national focus to guide detector dog activities, and they are supplemental to general operational procedures in the Airport and Maritime Operations Manual (AMOM)."
Scientific Working Group on Dog and Orthogonal Detector Guidelines (SWGDOG)
"SWGDOG is a partnership of local, state, federal and international agencies including private vendors, law enforcement and first responders. We anticipate that establishing consensus based best practices for the use of detection teams will provide many benefits to local law enforcement and homeland security. Improving the consistency and performance of deployed teams and optimizing their combination with electronic detection devices will improve interdiction efforts as well as courtroom acceptance." See Approved Guidelines; Documents for Public Comment; Appendices; and Bylaws.
Training and Certification Standards (National Narcotics Detector Dog Association)
"The National Narcotic Detector Dog Association (NNDDA) is a professional, nonprofit organization dedicated to the utilization and proficiency of scent detector dogs for the benefit of Law Enforcement and Private Industry. The purpose of the NNDDA is to provide training pertaining to the laws of search and seizure, utilizing scent detector dogs and a method of certification for court purposes."
Canine Tracking and Scent Identification: Factoring Science into the Threshold for Admissibility (SSRN 2010)
"The forensic value of dogs is enhanced by introducing the scientific aspects of their police work. The traditional tracking foundation is an adequate basis for delving into the various events that can occur while a dog is attempting to follow a perpetrator, but both prosecution and defense should recognize that many of the situations that can arise will implicate scientific issues that can help the trier of fact better understand the significance of the dog's behavior. Defense counsel should not merely accept the testimony of police handlers, and should be prepared to obtain equally reliable testimony of experts on the crucial issues presented in the facts. Courts should not accept harmless error arguments to shield defense lawyers who inadequately investigate the results obtained by the police and introduced into evidence by the prosecution."
Detector Dogs and Probable Cause, 14 Geo. Mason L. Rev. 1 (2006)
"This article argues that an alert, even by a well-trained dog with an excellent track record in the field, cannot by itself constitute probable cause to search."
Dog Law Reporter
"This blog is about the functions of and the laws that apply to dogs, particularly skilled dogs. We will discuss service dogs, therapy dogs, search and rescue dogs, police dogs and other working dogs. We will look at current research on dogs, such as that on dogs that detect cancers or alert to new types of explosives. We will ask how these changes are being accepted and understood and how these developments are translating into laws and regulations."
Drug Dogs---Reliability Issues and Case Law How Good Is That Doggie's Nose? (2007 Fall Public Defender Seminar, NC Office of Indigent Defense Services)
In this defender training piece, the following topics are addressed: I. Drug dog sniff is not a search under Illinois v. Caballes and North Carolina Law; II. Case Law Appears to Support a Requirement of a "Well trained" or "Properly Trained" Narcotic Dog for Probable Cause to be Found; III. Franks Hearing Regarding Drug Dog Alert; IV. What Do You Need to Ask for in Discovery to Attack the Dog's Nose?; V. Potential Areas and Ideas for Cross-Examination of Dog Handler.
Scent Identification in Criminal Investigations and Prosecutions: New Protocol Designs Improve Forensic Reliability (SSRN 2010)
"Scent lineups are a powerful tool in the investigation of crimes. With proper procedures, both forensic and judicial, scent lineups can be valuable evidence for a jury to consider. Unfortunately, many courts have been willing to admit poorly conducted procedures, even if giving lip service to the fact that the scent lineup was deficient by saying that its admission was harmless error. The tendency of some courts to view scent lineups as an extension of scent tracking has resulted in admission of scent lineup evidence under inappropriate standards."
State v. Carter: The Minnesota Constitution Protects Against Random and Suspicionless Dog Sniffs of Storage Units, 32 Wm. Mitchell L. Rev. 1287 (2006)
"This Article argues that Carter is an important decision for six primary reasons. First, Carter recognized that the protections against governmental intrusions are greater under the Minnesota Constitution than the protections afforded by the U.S. Constitution. Second, the court in Carter held that a dog sniff of a storage unit is not a search under the Fourth Amendment—an issue not yet decided by the U.S. Supreme Court. Third, Carter concluded that a dog sniff of a storage unit is a search under article I, section 10 of the Minnesota Constitution, declining to follow the U.S. Supreme Court's analysis that focuses almost exclusively on the nature of the item sought. Fourth, the court refused to extend Kyllo v. United States, which concerned the use of a thermal-imaging device on a home, to dog sniffs. Fifth, the court decided that the 'plain smell' doctrine does not apply to odors detected by dogs. Sixth, the court signaled that the potential for 'false alerts' from drug-detection dogs is a consideration in determining the constitutionality of this type of investigation. The decision in Carter sets clear limits on government intrusions—not only on the unrestrained and suspicionless use of drug-detecting dogs, but also on other emerging law enforcement investigative techniques as well." (footnotes omitted)
Those Doggone Sniffs Are Often Wrong: The Fourth Amendment Has Gone To the Dogs, Champion, April 2006, at 12
"This article will explore various ways in which, through litigating motions to suppress the fruits of searches conducted as the result of a positive dog 'alert,' defense counsel can educate courts, which are all too apt to reflexively credit the accuracy of canine alerts, regarding the serious flaws in much of the existing jurisprudence regarding canine sniffs and regarding modes of inquiry which more accurately reflect the reality of the interaction between dog, handler, and target."
3 See Dog, Wikipedia ("The olfactory bulb in dogs is roughly forty times bigger than the olfactory bulb in humans, relative to total brain size, with 125 to 220 million smell-sensitive receptors. The bloodhound exceeds this standard with nearly 300 million receptors. Dogs can discriminate odors at concentrations nearly 100 million times lower than humans can." (footnotes omitted)); The Dog's Sense of Smell, UNP-66, July 2005, at 1 ("In fact, a dog has more than 220 million olfactory receptors in its nose, while humans have only 5 million.")
8 See generally Illinois v. Caballes, 543 U.S. 405 (2005) ("A dog sniff conducted during a concededly lawful traffic stop that reveals no information other than the location of a substance that no individual has any right to possess does not violate the Fourth Amendment."); Use of Trained Dog to Detect Narcotics or Drugs as Unreasonable Search in Violation of Fourth Amendment, 150 A.L.R. Fed. 399; Use of Trained Dog to Detect Narcotics or Drugs as Unreasonable Search in Violation of State Constitutions, 117 A.L.R.5th 407.