The relevant Biblical text which is interpreted by the Jehovah's Witnesses as preventing them from taking blood transfusions comes from the Acts of the Apostles, chapter 15.
It deals with a dispute between Paul and Barnabas as to whether those who were not circumcised according to the law of Moses could be saved. The apostles and elders met in Jerusalem to discuss the matter.
Addressing them, Peter said that God had made no distinction between Gentiles and Jews, having purified all their hearts by faith. He denounced the idea and said "we believe it is through the grace of our Lord Jesus that we are saved, just as they [Gentiles] are."
James said it was his view that it should not be made difficult for the Gentiles who were turning to God. "Instead, we should write to them, telling them to abstain from food polluted by idols, from sexual immorality, from the meat of strangled animals and from blood [my emphasis]."
It is from this that the Jehovah's Witnesses derive their belief that blood transfusions are wrong.
Legally, their decision to do so can bring into conflict two fundamental principles: the right to life and the right to freedom of religious expression.
Where an adult is concerned, the conflict is less sharp, though it is still difficult for the authorities to deal with a decision to refuse a blood transfusion, as in some instances this could be construed as suicide, which is illegal.
However, where a child is in a life-threatening situation, and its parents decide for it in accordance with their beliefs, the conflict becomes acute.
The complexity of that conflict was commented on by Mr Donncha O'Connell, director of the Irish Council for Civil Liberties, last night.
He said "the difficulty of balancing religious freedom with the right to life is complicated by capacity and consent questions when the right to life in question is that of a child.
"While it may be perfectly acceptable for an adult, in pursuance of religious beliefs, to choose to forgo medical intervention, even if this results in death, it is altogether more problematic if that choice is made on behalf of a child.
"How can it be said that a child is exercising religious freedom when the choice of a child's religion [if any] is typically made by a parent?
"If that choice entails a threat to the life of the child, intervention by a third party is not as objectionable as it might be in another context."