Science you can sniff at?

Unlike other novel detection equipment, such as scanners, consent is not requested before a person is sniffed. According to BTP, this is because the use of a scanner amounts to a search, and a sniff by a dog doesn't. The BTP's reasoning is that a person has to walk though a scanner, whereas they don't have to walk past a dog.

In the Supreme Court case Kyllo v United States, the police use of a thermal imaging device was found to amount to a search because it revealed information that would previously have only been obtainable by physical intrusion. The Supreme Court reasoned that if the laws applicable to physical searches were not applied to searches made with sense enhancing technologies, the values enshrined in the law would cease to be protected with the advance of technology.

The Supreme Court failed to apply this reasoning to the use of the drug dog on the assumption that a drug dog was an infallible detection tool that picked up the scent of drugs alone, and that regulating its use would only shield information unworthy of protection. In his dissenting judgment, Justice Souter pointed out that: "The infallible dog...is a creature of legal fiction." He said "if constitutional scrutiny is in order for the imager, it is in order for the dog".

Are the police relying on the myth that "a dog never lies" to take advantage of false positives and obtain personal details of innocent citizens?

The BTP spokesman said dogs "are being used more and more because there are a growing number available and they are very useful. On being indicated by the dog, persons are stopped and searched and a record made containing their personal details and a physical description. Later, if there is a report of a robbery, the police can go through those records to see if it matches any of the persons known to have been in the area".

One US website describes this practice disparagingly as "pigs using dogs to fish humans". It is certainly a novel means of creating a database of potential suspects.

The use of dog indications to justify stop and searches has only recently come under legal scrutiny, and principally in the United States. In 2003, the District Court of Appeal in Florida (Matheson v State of Florida) found that the false response rate of dogs meant that an indication from a dog could not by itself provide the police with reasonable grounds to conduct a stop and search.

This decision threw the use of dogs as detection tools into disarray and in the ensuing controversy it emerged that dogs were regularly relied upon in courts to provide evidence of identification. Scent line-ups are conducted in which the dog is asked to match a scent from the crime scene to the scent of a suspect.

"People have been convicted of robbery, rape, and even murder when the primary evidence against them is, effectively, a bark."

According to Dr Jozef Wojcikiewicz, professor of Forensic Science, Department of Criminalistics, Jagiellonian University and Institute of Forensic Research, Poland, "canine identification of human scent does not yet have a proper scientific foundation...the method has been introduced into trial proceedings too early, by overly hasty police practitioners which have caused miscarriages of justice".

Since the court’s decision in Matheson v State of Florida, the research staff at the International Forensic Research Institute at Florida International University have been busily trying to provide "concise scientific validation of canine detection".

The institute has been generously funded over the years. On 17 February, 2006, it was awarded $246,634 by the US government "to design, develop and test a method to improve the performance and scientific defensibility of dog teams used for human scent identification".

"Scientific defensibility" is an interesting choice of words, presumably reserved for techniques with no scientific foundation. ®

Amber Marks is a barrister. She is undertaking doctoral research into olfactory surveillance with the Law Department and Forensic Science and Drug Monitoring Unit at King's College, London. Email your comments or experiences of sniffer dogs to her at amber.marks@gmail.com >