The term pit bull is a generic term used to describe dogs with similar physical characteristics. Usually a "pit bull" is considered one of several breeds including the American Pit Bull Terrier, the American Staffordshire Terrier, the Staffordshire Bull Terrier, Bull Terrier or any mix thereof. In some parts of the world, the American Bulldog and Dogo Argentino are also classified as a "Pit Bull-type" dog, despite major genetic differences. Any dog that is mixed with a "bully breed" may also be called a "pit bull" including those that are descended from the English Bulldog, French Bulldog, Boston Terrier and Cane Corso. The pitbull is not a distinct breed which may make it difficult for experts to identify, and while mixed breed dogs are often labelled a "pitbull" if they have certain physical characteristics such as a square shaped head or bulky body type, visual identification of mixed breed dogs is not recommended by the scholarly community. Several jurisdictions have enacted breed-specific legislation against pitbulls, ranging from outright bans on the possession of pit bull-type dogs, to restrictions and conditions on pit bull ownership. Research indicates that breed specific legislation is ineffective because it is not the breed of dog that is dangerous; rather, it is unfavorable situations that create dangerous dogs.