All in all a tricky subject, I totally agree that some provision should be made so that animals in good health, and a good state of mind, shouldn't be needlessly euthanized. Especially if there is someone waiting and willing to become responable for said animal!!
But on the other hand.... Sick animals do have the luxury of being Euthanized, and I do mean Luxury, my great Grandma was dieing incredibly slowly of terminal cancer, it was eating her up inside and there was nothing the doctors could do for her, except to watch her suffer. She was always a very proud lady and one day she said to one of the doctors making the rounds in the hospice "If I was a dog, you would take me to the vets, and I would leave in peace and dignity!" The doctor could do nothing but agree with her.
The last thing we would want is for this to happen to our animals, so any law would have to take Humane Euthanazia in to account, Not sure how that would work, as then how do you define "Humane" would it only be for dogs suffering from a critical illness, and then where do you place the cut off? Surely there would have to be a suffering scale, where minor suffering was ok, but once they had passed above and beyond the vet would be legally covered to euthanize??? It all becomes a question of how much is too much?
Just musing really.