Actually the person above specifically suggested it could also be mandatory, as this were an equally palatable option. So it was mostly that suggestion that I

Actually the person above specifically suggested it could also be mandatory, as this were an equally palatable option. So it was mostly that suggestion that I was responding to. As to the negative tradeoffs in that option -- I think they're pretty obvious. (Hint: we'd have to in effect force members of certain religious to at least formally disavow that aspect of their religion, for one). As to opt-out, while of course different, it's still in the same (troublesome) territory as the 'mandatory' option -- definitely a major insult to people with strong personal or religious convictions about the issue. At the end of the day, it's inseparable from the idea that your body is, on a certain level, state property. Which, aside from being repugnant to many people, is also in conflict with the emerging social consensus that, by and large, one's dominion over one's physical body is absolute and inviolable† -- which just so happens to form the legal and philosophical bedrock behind the idea that one should be free to choose to terminate a pregnancy; as well as (in the case of terminal illness, at least), the manner and timing one's own death; and of course, the manner in which one's body is disposed; The same should naturally hold for the disposition of one's organs after death. We would never think of passing a law making, say, chemical dissolution the default disposal method for your body after death, unless you "opt-out" and choose some other method -- even though this is touted to have many environmental benefits. Nor would we think to propose that, by default, your body be served up for whatever experimental purposes the local university might have in mind (unless you "opt-out", that is). It'd just be way to repugnant to many people, and open up too many cans of worms ethically and legally. So the organ donation issue is basically right in the same territory. † Aside from proscriptions against controlled substances, of course. But that's just one of the many schizophrenic negative tradeoffs of that particular policy.