From the No Kill Declaration's guiding principles, a joint project of the No Kill Advocacy Center and Alley Cat Allies:

No Kill is achieved only by guaranteeing the following: life to all healthy animals, and to all sick, injured, or vicious animals where medical or behavioral intervention would alter a poor or grave prognosis; the right of feral cats to live in their habitats. 

These conditions can be achieved only through adherence to the following: shelters and humane groups end the killing of healthy and treatable animals, including feral cats; every animal in a shelter receives individual consideration, regardless of how many animals a shelter takes in, or whether such animals are healthy, underaged, elderly, sick, injured, traumatized, or feral.

Nathan Winograd is one of the leading, and certainly most vocal, leaders of the No Kill movement, and currently serves as director of the No Kill Advocacy Center mentioned above.  I read a good portion of his influential book Redemption: The Myth of Pet Overpopulation and the No Kill Revolution in America (Almaden 2007), after my friend Lynda Stein graciously sent me a copy.  Following some illuminating historical perspective on the origins of the first U.S. humane society, Winograd makes a relentless and compelling case for how modern humane societies and shelters, national and local, have abandoned their core concern for preserving all of the animal lives under their protection:

How did the very charities founded on the highest ideals of compassion become the nation's leading killers of dogs and cats?  ... And why does the animal-loving American public ... not only accept this situation but continue to foot the bill for the daily killing of animals through taxes and voluntary donations? 

... For far too long, we have been led to believe there is no other way.  More than that, we have been told that this killing is the right thing to do. (pg. 1-2)

Winograd covers one justification after another for the millions of adoptable animals killed by shelters each year: there aren't enough homes, some animals just aren't desirable, the public is too disinterested or uneducated about how to take care of pets, and of course the space and expense which is required to keep animals alive.  Some of the institutional statements he quotes are simply hair-raising, such as a shelter director's 1990 PR stunt which involved the public euthanization of, among other animals, a healthy cat and her four kittens, which PETA at the time called "courageous." (pg. 5-6)

But Winograd affirms, even demands, that it doesn't have to be this way. He draws from the example of the San Fransisco SPCA's stunning transformation to a No Kill operation in the 90's (though it would soften its stance at a later point, unfortunately), and his own proactive experience converting an upstate New York SPCA to No Kill earlier this decade:

The next weekend, seventy kittens were relinquished to the shelter, above and beyond the regular number of incoming dogs, cats and other assorted animals (including sixteen mice left by our dumpster).  When the humane officers informed me that they had just raided a residence and were bringing in about thirty sick cats, I overheard one staff member say to another, "Maybe now he will euthanize some animals."  Back to square one.  I explained that killing for space was no longer an option.  Again, creative life-affirming alternatives were found, and nobody was killed. (pg. 95)

There is much more detail in Winograd's book than I could hope to summarize (this video interview goes a bit more into depth), but I hope the general thrust communicates.  It's one which has helped polarize the companion animal shelter and rescue community, fueling avid proponents of No Kill on one side of the fence (it's easy to join the ranks after reading Redemption), and generating heavy critique from those in the traditional sector who not only feel that they're doing their very best and have been unjustly vilified, but that No Kill is an unrealistic and even deceptive ideal to begin with.  We'll explore that end of the discussion more in the coming days.