This article compares the detection of forensic specimens by biological and instrumental methods. While detector dogs are still widely used, a variety of instruments are available and others are under development which hold the promise of being able to complement detector dog teams. Recent attacks on the reliability of detector dogs in the media and courtrooms has highlighted the need for more research and the need to better document the reliability of detector dog teams. Reliability should be assessed using objective measures in the same way that instrumental methods are evaluated using standardized methods. A comparison of current methods of evaluating detector dog teams is made and standardization efforts are discussed. Overall, the available data demonstrates that detection canine teams still represent one of the fastest, most versatile, reliable and cost effective real-time detection devices available to locate forensic specimens. Standardization efforts should further improve their capabilities and provide a roadmap for their most efficient combination with instrumental detectors.
The discovery of smuggled contraband and the location of forensic evidence at crime scenes increasingly requires the use of sophisticated detectors, such as detector dogs (canis lupus var. familiaris) or electronic sensors. The reliability of detector dogs, however, is increasingly coming into question in courts of law and in the mass media due to limited peer-reviewed research on error rates and a lack of best practice procedures for the certification and maintenance of detection teams. Legal challenges to the use of detector dogs, which have also been widely publicized, include suspected drug money, narcotics, explosives, cadavers and scent identification cases. A sampling of some recent by-lines include; "Dog Trainer Given Maximum Sentence for Fraud: Russell Lee Ebersole Convicted of Providing Bomb-Sniffing Dogs that Couldn't Smell Out Explosives" (Washington Post, September 8, 2003); "Bones of Contention: Cadaver-sniffing canine's finds are under suspicion" (Detroit Free Press, July 14, 2003); and "Sit! Stay! Testify!--Dogs have identified suspects in thousands of criminal cases. But how can we be sure that they're telling the truth?" (Fortune, January 26, 2004).
The United States Supreme Court rulings in the 1990's had a significant impact on the admissibility of forensic science evidence, including detector dog alerts, due to an increased demand for quantitative data regarding the reliability of results presented. In Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) the United States Supreme Court appointed trial judges as "gatekeepers" of expert evidence and offered them specific, but not exhaustive, factors to consider when evaluating the weight of scientific evidence presented by experts. So-called Daubert factors include: whether the scientific knowledge can be (and has been) tested, whether it has been subjected to peer review, the size of the known error rate for findings, and whether the knowledge enjoys widespread acceptance in the scientific community. This ruling was further clarified by the United States Supreme Court in Kumho Tire, Inc. v. Carmichael (1999) which established that the reliability criteria of Daubert should apply to all types of expert testimony, including non-technical expertise. This would include expertise based on experience and training such as the use of detector dogs and their ability to alert to drugs. It is argued, therefore, that scientific studies validating the capabilities of detector dogs will continue to increase the value of said alerts in courts of law. Recently, a number of articles have been published on the scientific validity of detector dogs trained to detect explosives, accelerants and humans (Furton & Myers, 2001; Furton & Harper, 2004; Curran et. al., 2005).
A prominent example of legal challenges to the use of detector dogs involves drug dog alerts to currency associated with drug trafficking. …