Full Title Name:  Scent Identification Procedures in the U.S. Have Different History and Different Procedures From Those Conducted in Europe

ABSTRACT

Scent lineups, designed to use a dog’s behavior to establish that two scents, one from a crime scene and one from a suspect, derive from the same person, have been conducted in radically different ways in the U.S. and Europe. In the U.S., scent lineups are often performed outdoors, in fields or parking lots, while in Europe they have for decades only been conducted indoors, often in canine forensic laboratories. In the U.S., lineups of individuals, as opposed to scents taken from individuals, have been part of standard practice in some jurisdictions until recently, but this has not been done in Europe for decades. Tracking of a suspect through a police station has been accepted as a formal identification procedure in the U.S., but not in Europe.  In the U.S., scent lineups are conducted by individual handlers, whereas in Europe they are conducted by teams that consist of a handler, an experimenter, and often other technicians.  In the U.S. the handler calls the alert, a behavioral response that may not be evident to other observers, while in Europe the experimenter generally calls the alert and it the dog’s alerting behavior must be evident to any observer. In the U.S., scents may be placed in stations that may be paint cans or other containers that are not or cannot be cleaned between trials, while in Europe stations are glass containers or metal tubes that are cleaned or replaced between trials. The position of the target scent (that of the suspect) must be moved randomly between trials in Europe, but not the U.S. In Europe, scents of decoys (foils) must be collected near the same time as the target scent is collected, but many handlers in the U.S. use decoy scents they have been preserved for years, which are often used against crime-scene scents that are only days or weeks old.  In Europe, there must generally be from three to five identification trials before positive alerts can be introduced in a criminal prosecution, whereas in the U.S., the results of a single trial have often been introduced in evidence. Treats as rewards are never given in official identification trials in Europe, but sometimes are in the U.S. Most U.S. scent identification dogs have been bloodhounds, while in Europe German shepherds and other shepherd types are preferred. Centralized European canine forensic laboratories where scent lineups are performed often conduct research in collaboration with forensic scientists, whereas U.S. handlers have not been participants in, or subjects of, research efforts.  Considerable data on the practices of U.S. handlers can be obtained from opinions issued by judges in criminal proceedings, and expert witnesses in those proceedings have come from canine specialists at the FBI and from American scientists who have conducted research on scent identification (both in support of and in opposition to the introduction of such evidence).  In both Europe and the U.S., however, use of the scent lineup to produce forensic evidence is in decline, and it may have come to an end in the U.S.