Someone said :
Opt in, opt out - it won't make any difference.
I disagree. An opt out system means everyone can be a donour by default, and therefore there will be far more potential donours.
I haven't done much research on this, but it seems the facts support my opinion.
Opt-in versus opt-out https://en.wikipedia.org/wiki/Organ_donation#Opt-in_versus_opt-ou etc ...
There are two main methods for determining voluntary consent: "opt in" (only those who have given explicit consent are donors) and "opt out" (anyone who has not refused is a donor). Opt-out legislative systems dramatically increase effective rates of consent for donation (the so-called default effect). For example, Germany, which uses an opt-in system, has an organ donation consent rate of 12% among its population, while Austria, a country with a very similar culture and economic development, but which uses an opt-out system, has a consent rate of 99.98%.
However, because of public policies, cultural, infrastructural and other factors, this does not always translate directly into increased effective rates of donation. In terms of effective organ donations, in some systems like Australia (14.9 donors per million, 337 donors in 2011), family members are required to give consent or refusal, or may veto a potential recovery even if the donor has consented. Some countries with an opt-out system like Spain (36 effective donors per million inhabitants) or Austria (21 donors/million) have high donor rates and some countries with opt-in systems like Germany (16 donors/million) or Greece (6 donors/million) have lower effective donation rates.[