I read with some irritation the Weasel's account of a ruling in the Court of Appeal on the admissibility of a dog's evidence (Up & Down Canary Wharf, 4 February). I have considerable experience of the training and olfactory prowess of police dogs, and agree wholeheartedly with Lord Taylor that corroborative evidence based on the behaviour of a well-trained dog, known to be reliable, is quite acceptable. The Weasel lightly suggests that this made the dog an acceptable witness in a court of law, which, of course, is nonsense. On comparable grounds he could have claimed that a pair of lines of dark blobs constituting two DNA profiles or a pair of fingerprints could also be called as witnesses.

In fact, the witness in this case was Ben's handler, a constable of the Thames Valley Police, who vouched for the reliability of her dog, just as an expert witness vouches for the reliability of a DNA profile or a fingerprint.

The handler's task would, however, have been easier if there was well- validated information on the routine training and performance of police dogs, and my colleagues and I hope to be able to supply this in the near future, so that British courts can begin to use a dog's evidence as routinely as the Hungarian, Dutch and German ones have been doing for years.

barbara sommerville

Department of Clinical Veterinary Medicine