Some doctors are to argue against moves towards an organ donation system of presumed consent in the UK.
Presumed consent would mean it would be assumed that people are in favour of donating their organs unless they have opted out.
Nowhere in the UK has introduced the scheme, but the Welsh Government is in favour of the idea and is expected to introduce a Bill to change the law during the current political term.
The British Medical Association (BMA) has been in favour of a "soft opt-out" system since 1999.
But delegates at its annual conference in Cardiff today will consider a motion to reconsider its policy - with those in favour saying such a move could damage trust in doctors.
Dr Sharon Blackford, a dermatologist from Swansea, is proposing the motion calling for the BMA to change its current position.
She said: "I and my colleagues are concerned if we move to presumed consent, it could damage trust in doctors. If someone is in intensive care, families may feel doctors just want to harvest the organs.
"It also goes against the whole idea of the moment - putting patients in charge. People may start thinking about it differently and it could turn people off."
More than 3,700 donations took place last year - a 5% increase on the previous year - but there are still about 8,000 people on the waiting list for transplants.
Over the past three years, the NHS has invested in specialist nurses to identify potential donors, as well as allowing for approaches to families when death becomes likely.
Dr Evan Harris, the doctor who first proposed the motion setting the BMA's policy on organ donation, said a system of presumed consent was better for patients, doctors and relatives of the donor.
"The vast majority of people would wish to help save lives after their death, but the problem is the current system sees nearly half of relatives withholding their permission because they are uncertain (of what to do)," he said.
"The evidence is very good that presumed consent is effective and acceptable in countries where it has been introduced."
The motion for the U-turn on the BMA's policy will be considered at its annual meeting in St David's Hall, Cardiff, today.