Proponents of the type and advocates of regulation have engaged in a highly contentious nature-versus-nurture debate over whether aggressive tendencies in pit bulls may be appropriately attributed to owners' poor care for and competency to handle the dog or inherent qualities owing to their breeding for fighting purposes.

[12][13]: 18, 49  Some insurance companies will not cover pit bulls (along with Rottweilers and wolf hybrids) because these particular dogs cause a disproportionate rate of bite incidents.

It was created by crossing the ferocious, thickly muscled Old English Bulldog with the agile, lithe, feisty Black and Tan Terrier.

[7][8][9] To produce a lighter, faster, more agile dog that retained the courage and tenacity of the Bulldog, outcrosses from local terriers were tried, and ultimately found to be successful.

[7][8][9] As it was in the UK, dog fighting became a popular pastime in 19th century America and bull-and-terriers were imported to the New World to pursue the blood sport.

[22][23] There is a lobby of animal rights groups that are spending millions of dollars to try to rebrand pit bulls as family dogs.

[37] However, DNA-based ancestry testing that works with owner-reported databases can be unreliable and the American Kennel Club does not recommend using those.

[36] For example, the Manawatū District Council does not accept DNA heritage testing for pit bulls, instead they look at a dog's certain physical traits.

[64][65][66] Mixed-breed dogs are often labeled as pit bulls if they have certain physical characteristics, such as a square-shaped head or bulky body type.

[73] In a 2021 review of 19 retrospective dog bite studies from U.S. Level I trauma centers, pit bulls were found to inflict a higher prevalence and severity of injuries compared with other breeds.

The pit bull proportion of dog bites increased more slowly in Denver, Colorado, where breed-specific legislation had been in place.

[76][78] Bite statistics by breed are no longer tracked by the CDC,[79] and are discouraged by the AVMA[80] and the American Society for the Prevention of Cruelty to Animals (ASPCA).

[82] However, recent research suggests that this perception may reflect a lack of knowledge of dog body-language, and owners' over-confidence in their ability to interpret those signs.

[85] Violent interactions between humans and canines have been studied by the U.S. government,[86] notably the Centers for Disease Control and Prevention (CDC),[87] as well as academic veterinary researchers.

[92] Pit bull–type dogs, like other terriers, hunting and bull-baiting breeds,[93] can exhibit a bite, hold, and shake behavior and at times refuse to release.

[99] Surveys have found that animal shelter workers intentionally misidentify pit bulls to improve their adoption rates, or to avoid euthanizing them in jurisdictions where they are banned.

[100] Animal advocates recommend that shelters stop labeling breeds to improve pit bull adoption rates.

[99] Pit bulls also have higher rates of unsuccessful adoptions, and are more likely than other kinds of dogs to be returned to a shelter multiple times and eventually euthanized.

[99] Widely reported pit bull attacks have resulted in the enactment of breed-specific legislation (BSL) in several jurisdictions.

[103] Research has indicated that there is resistance by those who work in the adoption industry, applying a sharper distinction before allowing a dog to be labeled as a pit bull, as well as objections from veterinarians.

Courts in the United States[109][110] and Canada[111][112] have ruled that expert identification, when using published breed standards, is sufficient for the enforcement of breed-specific legislation.

Debates often center on whether apparent aggressive tendencies are the result of poor dog ownership or natural behaviors of the breed.

[104] Under Irish law, American Pit Bull Terriers must be led by someone at least 16 years of age, kept on a short strong lead, be muzzled, and wear a collar bearing the name and address of their owner in public at all times.

The dogs are permitted under a system of exemptions that are contingent on owners complying with special rules, such as muzzling them in public and having liability insurance.

[116] Seventeen U.S. States prohibit local governments from enacting breed-specific ordinances: California, Colorado, Connecticut, Florida, Illinois, Maine, Massachusetts, Minnesota, Nevada, New Jersey, New York, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Texas, Utah, and Virginia.

[120][better source needed] In 2013, Farmers Insurance notified policyholders in California that it would no longer cover bites by pit bulls, Rottweilers and wolf-dog hybrids.

[138] The White supremacist group Keystone State Skinheads have used a specific graphic of a pit bull as their logo.

[142][143] In 2005, two American lawyers used a pit bull logo and the phone number 1-800-PIT-BULL in a television advertisement to convey that they were "especially fierce litigators".