Making donation the 'default option' is a powerful force and should propbably be a goal. There are many organ donor schemes (with a driver's licence, for example) but all have a default setting of not donating and require that someone choosing to donate organs must make a special effort like obtaining two witness signatures. This is not as trivial as it sounds - a spouse might be one witness, but then who else do you want to discuss this with. Many people might donate but haven't made those extra steps. We could start by making the existing process easier (Why do we need two witnessses? Why isn't my signature alone enough to indicate my wishes?), but to really get effective donation rates I think we need to be more radical. I sugest we push to reverse the default choice and make the burden of extra effort fall on those who don't wish to donate (so everyone is a donor unless they choose not to be). This naturally requires that opting out be very easy indeed (just checking a box perhaps).