Drug-sniffing dogs aren't just often inaccurate, they are extremely susceptible to the influence of their handlers. Search points designed to trick the handlers into believing there were narcotics present were twice as likely to trigger false alerts as those used to trick the dogs. More than just drug searches, canine testimony has been key in the conviction of murder suspects whose scent was supposedly left at the crime scene. There have been multiple lawsuits against police by those who say they were wrongfully convicted by such means. Learn more from the SavvyRoo chart linked in the source!

This figure is much, much higher than I would have guessed it to be. Knowing that proportion of false positives, 'following your nose,' or that of your K9 may cause a host of unforeseen ethical and legal dilemmas.