Dog-Scent Investigations and the DefendantIt is not uncommon for law enforcement agencies to use trained canines on a crime scene to recognize and match smells. This is known as dog-scent identifications. The dogs are used to identify people involved in a crime, as well as different substances, by smell. A dog can sniff around a crime scene and later match a person to the crime scene by his or her scent. Dog-scent identification can be presented at trials as evidences against defendants.

How Does Dog-Scent Identification Work
Often, an expert is called in to discuss dog-scent identifications, if dog-scent identification information is being presented as evidence during a trial. Because dog-scent identifications are not always reliable, judges actually reject dog-scent evidence sometimes. If dog-scent information is going to be used at trial, the police and prosecuting attorney must follow proper protocol for presenting it as evidence. Dogs, just like people, do make mistakes. Dog-scent evidence is prone to error just like many other forms of scientific analysis. When there’s a specific reason to doubt the accuracy of evidence pointing to a defendant’s guilt, the defense has a right to question it and conduct research regarding the matter. The criminal defense attorney can find out if the dog used made any errors in the past in identifying offenders, for example. At times, a judge won’t allow the dog-scent evidence if the defense lawyer can show the information is flawed.

False Conviction Due to Dog-Scent Identification
A 9th U.S. Circuit Court of Appeals panel recently ruled that evidence used to convict Aguilar of murder was not valid because prosecutors failed to disclose a police dog’s history of mistakenly identifying scents. Aguilar was convicted of first-degree murder in 2002 in the case of Aguilar v. Woodford based on the scent-matching evidence provided by a dog named Reilly. In a trial just months earlier, it was revealed that the scent dog had mistaken identities in the past. This information, however, was not disclosed to Aguilar’s defense during his trial even though evidence was used concerning Reilly matching Aguilar’s scent to the getaway car. Because of this fact, the court of appeals ordered that Aguilar receive a new trial or be released.