Dogs have been selectively bred for thousands of years, sometimes by inbreeding dogs from the same ancestral lines, sometimes by mixing dogs from very different lines. The process continues today, resulting in a widening in appearance without speciation, "from the Chihuahua to the Great Dane."
Before you say that the person in California could find another dog closer to home, what if the New Jersey breeder is one of the few people in the country breeding that particular breed? In many cases we are talking about breeds that may only register a few litters per year. That’s why this kind of legislation is so dangerous. In some cases it could literally cause the extinction of breeds. Breeders give up breeding rather than face these kinds of legislative problems.
For example, a bill currently under consideration in New Jersey would ban breeders from selling dogs outside the state unless the sale was made face-to-face. If you are a breeder in New Jersey and a potential buyer in say, California, is interested in one of your dogs, this buyer would have to come to New Jersey to see and buy the dog. Or the breeder would have to take the dog to California. This is obviously onerous and unnecessary. It also adds a tremendous expense to the cost of the dog. This kind of legislation is proposed in the name of “consumer protection” but it is actually meant to punish and discourage dog breeding.
That’s why we need breeders of purebred dogs today. People who breed to preserve dog breeds are usually hobbyists. They may participate in dog shows or companion/performance events with their dogs. The dogs that they can’t keep are usually placed in pet homes. Yet cities and state legislatures are passing laws that can make it virtually impossible for smaller breeders to continue this important work.