It's perfectly legal to train a dog to set, it's not legal to set them on somebody without sufficient cause to feel threatened. It's perfectly legal to own a hockey stick but it's not legal to wrap it around somebody's head without due cause. If you have a trained attack dog that bites somebody you may have to pay out damages in a civil case but you won't face criminal charges, unless there's evidence that you deliberately caused the dog to bite someone. Trust me, been there, done that, got the t-shirt (€32,325 is a lot of money for a t-shirt but it's on an installments plan with the insurance company).