The answer is in Rick Sargent's question to the members of the board of the BC SPCA. When did the SPCA decide that its mandate was to protect humans from animals, not animals from humans?
In the last few years, the BC SPCA has become hard-nosed about any dog that might bite. It has hired "scientists" to devise a test to enable it to prove that many dogs must be killed to protect the public. This attitude is about "control", not "welfare", and the attitude is hardening.
It is true that some dogs are not rehabilitatible, but very few. Sophie was a puppy. And a very experienced Springer Spaniel rescuer offered to take her. That the SPCA killed this puppy instead is what is wrong with the SPCA.
I am astonished that anyone feels sorry for the SPCA or can excuse it in any way. It chose the role of animal control. It chose unlimited surrender. It chose to try to protect itself from legal liabilty by saying that it has a duty to kill any dog that might bite.
As Rick Sargent pointed out, by publicly assuming a duty to protect the public, it can now be sued for not doing that.
No one who chooses the death of a puppy over an offer of rehabilitation is doing animal welfare. If you are afraid of a lawsuit, just stick to cats and gerbils.