There is an Official Breed Standard for every purebred, recognized breed of dog. Although those standard may have some variations depending on the registry, the purpose of the Standard is the same. The Official Breed Standard is a written description of the ideal dog of that breed.
These standards were not written by a single person, or written on a whim. The standards are full of history; dating back to the earliest recordings of the breed. Earliest standards have been changed, of course. Changes to the standard are now made by committee decisions, and then must be approved by the Parent Club, and then channeled through the AKC. No changes are made without a proven need, and most changes are in the form of clarification.
As breeders, we have a responsibility- no- an obligation to breed to the standard of our breed. The points in the standard describe what we call Breed Type. Those things that make our breed different from all of the other breeds- what makes a Cardigan different from a Pembroke- or a Bassett Hound! Breed Type encompasses many things: Silhouette, front, structure, balance, color, coat, head style, tail set & tail carriage, bone, etc. etc.-- and movement. Breeding to the standard means that your dogs are recognizable as Cardigans from a distance as Cardigans; no one is confusing them for corgi-mixes or border-corgi's.
But breeding is not an exact science, and certainly not every puppy born is going to ooze breed type. The reputable breeders work hard to follow the "rules." Breeding soundest, healthiest, best example of the breed (the bitch that is the closest to the standard) usually gets you closer to your goal, than breeding a mediocre bitch with glaring breed type faults. By the same token, breeding dogs with disqualifying faults is not breeding to improve.
Cardigans list 5 Disqualifying faults, 4 of which are what I consider "breeding no-no's" (and this is just my opinion):
Blue eyes, or partially blue eyes, in any coat color other than blue merle.
Nose other than solid black except in blue merles.
Any color other than specified.
Body color predominantly white.
Why are they no-no's? Because they are going to always be there in the pedigree- and they will come back to bite me-- or some other breeder down the line-- and they are disqualifications according to our current AKC Standard! Breeding decisions are very personal, and are completely tied in to a persons ethics. This is just where I have drawn the line for myself.
Official Breed Standards are very important for the history and the future of our breeds, and our sport. We expect Judges to make their choices in the ring according to the Standard. We educate those judges using the Standard, and we select dogs as examples of the breed, to educate those judges, using the Standard as a guide. Does it not make sense, then, for breeders to shoulder the responsibility and adhere to the standard when making breeding decisions?