Using K9s for scent discrimination has been part of the forensic repertoire used to solve crimes for a number of decades in several European countries. Over the years, police forces have refined their approach to scent discrimination to reduce errors and make it as legally accountable as possible. Authors Adee Schoon and Ruud Haak emphasize that the dog does not pinpoint a suspect as the perpetrator, but merely indicates that there is or is not a scent connection between crime-scene evidence and the suspect. They provide detailed training methods and working methodologies for handlers who want to train their dogs in this important work, as well as procedures for gathering scent evidence from the scene of the crime. A detailed history also shows how methods have developed over the years, and why some procedures were no longer acceptable and needed to be changed.