Ar 1 Rhagfyr 2015, Cymru oedd y wlad gyntaf yn y DU i gyflwyno system feddal o optio allan ar gyfer cydsynio i roi organau. O dan y system hon, os nad yw unigolyn wedi cofrestru penderfyniad i roi organau (optio i mewn) na phenderfyniad i beidio â rhoi organau (optio allan), ystyrir nad oes ganddo wrthwynebiad i roi ei organau – gelwir hyn yn gydsyniad tybiedig. Fodd bynnag, os nad yw'r unigolion yn trafod eu penderfyniad i roi organau â'u hanwyliaid, mae perygl i'r teulu beidio ag anrhydeddu'r penderfyniad hwnnw ac anwybyddu'r gofrestr rhoddwyr organau neu wrthwynebu cydsyniad tybiedig.
On 1 December 2015, Wales was the first country in the UK to move to a soft opt-out system of consent to organ donation. This means that if a person has not registered a decision to become an organ donor (opted in) or a decision not to become an organ donor (opted out), they will be considered as having no objection to being an organ donor – this is known as deemed consent. However, if individuals don’t tell their family of their decision to donate, the family may not honour that decision and over-ride the organ donor registration or not support deemed consent.