ABSTRACT
Tracking and trailing evidence has been admitted by courts in the United States since the end of the 19th century, but the foundational requirements established at that time were not based on judicial standards regarding the admission of scienti c evidence. Rather, courts accepted the long tradition, the “common knowledge,” of the use of bloodhounds in nding fugitives and criminals, which in England goes back to the Middle Ages.2 As forensics sciences developed, and courts began to expect that evidence with a scienti c basis should be supported by the testimony of experts with appropriate credentials, canine testimony began to face new hurdles. This chapter focuses on the development of the research relevant to the use of dogs in nding and identifying criminals, and discusses the introduction of the ndings of that research into criminal prosecutions.
