Families would have no legal right to stop dead relatives’ organs being used for transplant if the person has not opted out in advance, under a proposed Welsh law.
However, Health Minister Lesley Griffiths said she could not see a situation where doctors took organs without the permission of families.
Ministers are asking for views on plans for a “soft opt-out”.
If it goes ahead, Wales would be the UK’s first country with the system.
Ms Griffiths said the lack of organs and tissues caused unnecessary deaths and suffering.
The law, planned to be in place by 2015, would require people to opt out of donating their organs when they die, rather than opting in by signing the register.
Doctors’ leaders hope it will “change cultural expectations” and prompt more family discussions about donation.
Ms Griffiths said, in practice, she did not think the proposals would mean families losing the ability to refuse the organs of loved ones being donated.