According to this news article, a 25-year-old Ohio man was arrested for barking at a police dog. The dog had been left inside the cruiser while his human partner investigated an automobile accident. The dog's tormentor (in a state of significant intoxication) began barking and hissing at the police dog. The dog responded by barking back. The dog's handler responded by charging the drunken man with a misdemeanor.
When asked why he was teasing the dog, the man said, "He started it." We'll have to see if that defense works when he comes to court on April 21, 2011.
Personally, I'm rooting for the dog.