Hundreds of potential transplant operations are blocked by families who veto donation even though their loved one was on the donor register, doctors have warned.
Persuading more families to approve organ donation would improve transplant rates more than any other factor, they said.
More than 10,000 people in the UK are currently waiting for an organ transplant and each year around 1,000 will die due to a lack of organs.
Doctors from the Royal Victoria Infirmary in Newcastle found that overall four in ten families do not consent to organ donation when their relatives are declared brain-dead but are being kept alive by machines.
But even when the wishes of the patient were known because they were on the organ donor register, many families still refuse to allow donation.
DONOR REGISTRIES IN THE UNITED STATES ARE LEGALLY BINDING; A DOCUMENTED ANATOMICAL GIFT WHICH GUARANTEES DONOR'S WISHES WILL BE FULFILLED AND MAY NOT BE OVERRIDDEN BY FAMILY MEMBERS. IT IS THEREFORE VERY IMPORTANT THAT ONE REGISTER WITH THEIR DONOR REGISTRY OR DMV.