So just how dangerous are pit bulls?

The American Temperament Testing Society evaluated 122 breeds and found that the American Staffordshire Terrier, a type of banned pit bull in Denver, passed 83.3 percent of the time, just behind the golden retriever (83.6 percent).

The American Canine Foundation calculated rates of human dog-bite fatalities by breed and found that pit bulls bite at a lower rate than many other dogs. A Doberman Pinscher bites 10 times as much as a pit bull, the foundation reported.

Still, pit bulls and rottweilers have caused the most deaths, according to a study by the Centers for Disease Control and Prevention, the American Veterinary Medical Association and the Humane Society of the United States, which examined 20 years of dog-bite data.

That same study concluded fatal attacks "represent a small proportion of dog bite injuries to humans, and therefore, should not be the primary factor driving public policy concerning dangerous dogs."

Julie Gilchrist, a CDC doctor who researches dog bites, said many factors go into biting risk, including the health of the dog and how the animal was raised.

A Denver district court ruled in 1990 pit bulls can be treated differently than other dogs because "there is credible evidence that pit bull dog attacks are more severe and more likely to result in fatalities."