(Warning: graphic content)
Update: Additional post on the subject here.
South Carolina Code of Laws - Title 47, Chapter 3, Article 13, Section 47-3-710: (C) An animal is not a "dangerous animal" solely by virtue of its breed or species.
MYTH: American Pit Bull Terriers lock their jaws.
Dr. Brisbin: "The few studies which have been conducted of the structure of the skulls, mandibles and teeth of pit bulls show that, in proportion to their size, their jaw structure and thus its inferred functional morphology, is no different than that of any breed of dog.
There is absolutely no evidence for the existence of any kind of "locking mechanism" unique to the structure of the jaw and/or teeth of the American Pit Bull Terrier.
National Research Council has a pdf pamphlet available called "Your Dog's Nutritional Needs - A Science-Based Guide for Pet Owners"***