The Morality Of Organ Donation

A reader writes:

I do think it's worth pushing  questions about the provision of organs further back, to ask on what basis those who need those organs translate that need into a moral claim on society itself. Not all needs, including those needs which preserve life, are ipso facto understood (especially in the US, which lacks universal health care) as morally deserving of the resources of the society in general or of individual persons in particular.

So, a couple of questions, I guess: On what basis are the class of people in need of organ transplants deserving of those organs? On what basis are the class of people in need of organ transplants more deserving of having their needs met than the class of people with other life-threatening needs? On what basis does a need become a moral claim?

Again, I'm opposed neither to donation nor to efforts to make more organs available for transplantation, and as someone who supports universal health care and a more generous welfare state overall, I'm also not opposed to recognizing the moral content of a variety of needs. I simply believe that an argument in favor of such recognition has to be made, rather than presumed.