For the same reason, civil rights groups are alarmed at the trend to fit metal teeth, which they say is aimed as much at intimidating people as it is the welfare of the dogs. Emily Whitfield, a spokesman for the American Civil Liberties Union, said: "Innocent bystanders and witnesses to crimes have been attacked by police dogs by mistake. It's bad enough being chased by a dog with just an ordinary set of teeth. Metal fangs just up the ante and seem to us to be overkill."