What factors affect the legality of a dog sniff at a traffic stop?

A new decision by the United States Supreme Court limits the ability of police officers to use a dog to sniff the outside of a vehicle during a traffic stop. Years earlier the Court had held that during a lawful traffic stop, the police may use a trained dog to sniff an automobile, as long as the procedure does not unreasonably extend the duration of the traffic stop.

In the recent case, a police officer pulled a car over for a vehicle and traffic violation. He then verified that the driver had the required license, registration and proof of insurance, and gave all the documents back to the driver. At that point, he asked the driver for permission to have his canine drug detector walk around the car.

The dog alerted to the presence of drugs and a search of the vehicle revealed a large bag of methamphetamines.

The Supreme Court held that once the officer had completed all his tasks associated with the traffic stop - inspection of the driver's records - it was unlawful to utilize a dog sniff. The canine sniff is a tool for detecting evidence of a crime and that is not a proper part of a routine traffic stop.

The Supreme Court has also held that when the prosecution uses evidence obtained from a canine sniff, a defendant has the right to challenge the dog's reliability in detecting drugs. This can be done by either cross-examining the police officer or introducing the defendant's expert to contest the adequacy of the dog's certification or the dog's training program.

The many factors involved in a dog sniff of a vehicle may involve unlawful searches by a police officer and a person may want to consult with a criminal defense attorney to review the details of the case.