In comments to an earlier post, commenters "John D." and "Anonymous" had an exchange about whether legalizing organ sales would increase illegal kidnapping and theft of kidneys.
It is likely an empirical question, I suppose, but here is a story of such theft, not hypothetical but real.
I think both sides have a point here. First, it is quite true that in societies with poorly developed property rights and government protection, making organ sales illegal won't protect anyone. If you can get away with kidnapping, you can get away with a lot of things.
But John D. has a point also. Kidneys don't come with bar codes identifying their source. If the trade is international, it is quite possible that legalizing the purchase of kidneys by a first world buyer will result in more kidnapping in third world countries. One cannot assume that the act of legalizing sale will also create effective police protection and other civil institutions.
I don't think this is a good argument against legalizing kidney sales WITHIN the US (i.e., US donor, signs consent, euvoluntary exchange). But it is pretty good argument against legalizing purchase by Americans of kidneys "harvested" in the third world.