Stephen Dubner looks closer at a BMJ opinion on the subject:
Now for the dialysis patient. Let’s say she’s on a waiting list for a new kidney. But there is a good chance she’ll die before receiving a kidney, since far too few organs are being donated through traditional means to satisfy the demand. What happens, however, if instead of assuming that people do not wish to donate their organs in the event of an untimely death, you assume that they do? The latter option is known as presumed consent, and is practiced in some European countries. How well does it work?
