Coroners are refusing to test for an infection which causes vCJD - despite government pleas that it could help protect the public, the BBC has learnt.
Scientists said the checks during post-mortem examinations could help find out how many people in the population have the infection without knowing it.
This would help decide whether current measures to protect blood transfusion and surgical patients are sufficient.
But coroners claimed doing such tests could undermine their neutrality.
vCJD arose in the population in the 1980s as a result of eating beef from cattle infected with BSE.
Since then 164 people have died of the disease - however scientists still do not know how many people could be carrying the disease without showing any symptoms.
And it may well be that the cases so far are of those who are particularly sensitive to the disease and many more could die.
The body responsible for advising ministers on the issue - the Spongiform Encepalopathy Advisory Committee (SEAC) - told the government two years ago that it was important to find out how many people were silently carrying the infection.
The only reliable way of doing that, they said, would be to ask coroners to test the brain and spleen of young people during autopsies so that they could be tested for the presence of the infectious agent-known as a prion.
According to a member of SEAC, Professor John Collinge, systematic testing was needed to establish how many more people were likely to get the disease and whether the current measures to protect the spread of infection through blood transfusion and surgery were appropriate.
"I would hope that they would be able to help with this because I don't see any other way for us to get this information at the moment."
The Coroners' Society of England and Wales refused to comment.
But the BBC has learnt that the organisation has argued that the sole job of coroners was to identify the deceased and establish the cause of death.
The society has told officials that if they were to request consent from relatives to carry out research it would compromise their neutrality and breach the trust they have built up with the public.
The organisation is also concerned that if they were to agree to this request it would be the thin end of the wedge and lead to more requests for them to carry out research.
Dr Michael Powers, a QC and expert in coroners' law, said: "There are acts and rules which govern what coroners can and can't do. This would be an added extra, outside their legal framework."
But he added it could also be a question of money.
"It may well be that it could be done but for it to be done the coroners would have to be given more resources than they are presently being given"
Christine Lord, whose son died nearly two years ago of vCJD, urged coroners to carry out the tests as it had the potential to "save lives".
"I don't know whether it's to do with extra money or its rhetoric and bureaucracy getting in the way once again of protecting human health."
But the Department of Health said it hoped to begin a pilot scheme later this year to try out a system that it hoped would address many of the coroners' concerns.
A spokesman said: "The Health Protection Agency is running the pilot with the co-operation of NHS Bereavement Services and NHS Blood and Transplant's consent team.
"Some coroners have agreed to participate in the pilot study and appropriate funding will be made to them and to the other organisations incurring additional costs."
Categories: Inquests and Inquiries