Since doctors first performed human-to-human transplants in the 1950s years ago, the moral and practical questions about organ donation have been an emotive topic. 

This week, Switzerland voted to change its organ donation system to 'opt-out' – meaning citizens will be presumed to want their organs donated for transplant when they die, unless they tell authorities or their family they wish to opt out of the system.

It's a significant change from the 'opt-in' system, under which citizens fill in paperwork to register as an organ donor, and upon death doctors check if the deceased is on the transplant register or not. 

READ MORE

What is NATO and why is Russia worried?

Boxing away stress in Kyiv

What can Finland's military offer NATO?

Families still have the final say on organ donation in most 'opt-out' systems, including the new model in Switzerland. 

But how widespread is this mindset and policy? And does it increase organ donation? 

Across Europe the presumed consent or 'opt-out' model is more popular than 'opt-in.' Only five countries in the EU require citizens to register as organ donors. 

Outside the EU, Switzerland joins much of the UK (Northern Ireland remains opt-in) in changing to the policy aimed at increasing organ donations. 

"There has been tremendous progress in organ donation but there is still a shortage of donors," England's National Health Service explains on its website. "Wales introduced an opt-out system in 2015 and has seen an increase in the number of families supporting a loved one's decision to donate, resulting in more life-saving transplants for those in need."

Although 'opt-out' is widely seen as a policy designed to increase donations, there is little conclusive evidence that it is responsible for the increases in organ donation over the past decade. 

A 2018 paper by University of Birmingham academics found "no significant difference" in the 35 OECD nations they studied (17 countries classified as opt-out, 18 classified as opt-in). 

Although it focused primarily on kidney donations, the study also took a snapshot of the wider organ donation system. Quite simply, it is "too complex to simply link opt-out or opt-in directly with organ donation rates," it found. 

Instead, the public's "apathetic attitude and behavior" towards transplants and organ donation is "critical."

"The disconnect between the wish for organ transplantation (if ever required) but simultaneous reluctance to be organ donors (if ever possible) simply will not change with a move to presumed consent."