The case of R v Woollin  4 All ER 103 is the authoritative case on intention. In Woollin, the test of virtual certainty is developed from the principles of R v Nedrick11 . In Woollin, a father threw his baby son against a wall which resulted in the baby's death. Despite the father having no desire to kill his son, it was established that it was a virtual certainty that this result would occur and so the father was convicted of murder.
With reference to this case, the justices in Re A were shown that even though the doctors would not desire the death of Mary, they were sure it would take place as a result of their actions and so were still responsible for it. Having ascertained that both twins were entitled to their right to life, it was stated that the twins' doctors now faced a conflict of duties. The medics owed both Jodie and Mary equal duties of care but how could the doctors do what was in Jodie's best interest and what was in Mary's best interests?
The judges admitted that Jodie's best interests had to be for the operation to take place so that she may lead a normal life, but Mary's best interests would be for the operation not to take place as she would then have a longer life, even if it was by just 3-6 months. Because of this, the court decided to carry out a balancing exercise, to weigh up each twins situation and then act on the least detrimental. By doing this, the operation could be made lawful as the doctors would be carrying out the lesser of two evils. Finally, the reasoning behind the final decision by the court in Re A, needs to be discussed.
All three agreed judges agreed on the basic rule of the balancing exercise and the lesser of two evils approach. However, Ward LJ's reasoning seemed to lean towards the concept of quasi self-defence. He stated how, even though Mary could not be referred to as an 'unjust aggressor' she was still a threat to Jodie's life, and therefore with the outline of the concept of self defence being that there is an active threat by B on A and A acts to protect himself, this principle is applied by Ward LJ in the theory that the doctors could act in quasi self defence to save Jodie from Mary. Next is Brooke LJ's theory on necessity.
He states a change to the doctrine of necessity as the reason to allow the operation. Reference to the case of Dudley and Stephens 12 highlights the precedent in law that necessity cannot be used as a defence to murder, however, the court for Re A uses it as just that. They were able to do this because of the lesser of two evils principle which they already had in place, the very doctrine of necessity is based on the choice of one kind of evil over another. Brooke LJ was able to show that the requirements for the doctrine of necessity were filled by Re A and that the facts of the case were distinguished from Dudley and Stephens.
"An act which would otherwise be a crime may in some cases be excused if the person accused can show it was done only in order to avoid consequences which could not otherwise be avoided, and which, if they had followed, would have been inflicted upon him or upon others whom he was bound to protect from inevitable and irreparable evil, that no more was done than was reasonably necessary for that purpose, and that the evil inflicted was not disproportionate to the evil avoided…
"By adhering to this definition, the chance for Jodie to lead a full life outweighed allowing Mary to live for a few more months. Brooke LJ is quick to state that Re A is a unique case and that Dudley and Stephens remains the authority on necessity as the material facts of the cases are so different. Lastly, the judgement of Robert Walker LJ needs to be considered.
Although he agrees with his colleagues on the application of the doctrine of necessity, he also revisits the question of whether the operation would be in Mary's best interests. The conclusion that it would be was arrived at by the previous Johnson J, but was dismissed by Ward and Brooke LJJ, however, Walker LJ applies the question of bodily integrity to the question of Mary's best interests and suggests that as conjoined twins, both children have been denied the whole bodily integrity that they are entitled to by nature.
Because of this, Walker LJ suggests that; "The operation would give [Mary], even in death, bodily integrity as a human being. " 14 Therefore, by proceeding with the separation, even though she would die, Mary would finally be given the bodily integrity which is her right whereas if both twins were left to die in the following three to six months, this integrity would never be granted to either of them.
In conclusion, it is clear that, although varying routes were taken to get there, the same decision was eventually reached by Ward, Brooke and Walker LJJ that the appeal should be dismissed and that the operation to separate Mary and Jodie could go ahead lawfully. It could also be stated that the fact that each justice did explore a slightly different perspective on the case and still come to the same conclusion, strengthens the correctness of the overall judgement as it gives it several different reasons to be correct.
Re A (children) (conjoined twins: surgical separation)  4 All ER 961 Airedale NHS Trust v Bland  1 All ER 821 R v Dudley and Stephen (1884-5) 14 QBD 273 R v Woollin  4 All ER 103 Bloy, D. Lanser, D. Molan, M: Modern Criminal Law; 5th ed, 2003. Cavendish Publishing Limited. Curzon, L. B. Dictionary of Law; 6th ed, 2002. Pearson/Longman. Glazebrook, P. R. Statues on Criminal Law; 2003-2004. Blackstone's. Heaton, R. Criminal Law; 3rd ed, 2001. Blackstone's.