The Court of Appeal’s decision in Re A (conjoined twins: surgical separation) [2000] 4 All ER 961 presented an unprecedented legal and ethical dilemma. The case concerned craniopagus twins, Jodie and Mary, where separation was required to save Jodie but would inevitably cause Mary’s death. The judgment’s ratio decidendi—the legal principle upon which the decision is based—can be interpreted in both narrow and broad terms. This analysis will outline these differing interpretations, evaluate which is more defensible, and explore how a change in the facts would have altered the outcome.
The Narrow Ratio
A narrow interpretation of the ratio decidendi confines the legal principle strictly to the specific facts of the case. It can be formulated as follows:
Where two twins are conjoined, and one (J) is capable of independent life but the other (M) has a non-viable brain and is physically dependent on J for survival through a common artery, and where without separation both twins will inevitably die within months, it is lawful for doctors to perform a separation surgery which will save J but will also hasten the certain death of M, even where the parents refuse consent.
The facts material to this narrow ratio are highly specific. Firstly, the twins were conjoined in a way that made one entirely dependent on the other for life-sustaining functions (Ward LJ, p. 1002). Mary had no effective heart or lung function of her own. Secondly, Mary’s brain was "primitive" and she had no prospect of a separate or conscious existence. This was crucial, as the judges viewed her life as already "doomed" (Brooke LJ, p. 1069). Thirdly, the prognosis was certain: without the operation, both twins would die. The operation offered Jodie the prospect of a relatively normal life. Finally, the parents’ refusal of consent created the need for the court’s intervention. These facts are material because they combine to create a unique situation where the operation could be framed not as an active killing, but as a withdrawal of support from a non-viable individual to save another.
The Broad Ratio
A broader interpretation abstracts a more general legal principle from the judgment. This could be stated as:
It is lawful to kill person A to save the life of person B if person B will otherwise certainly die, and the life of person A has a significantly lower quality or potential than that of person B.
The material facts for this broader ratio are less specific. They include: the certainty of death for both individuals without intervention; the fact that an action can save one but will kill the other; and an implicit judgment on the comparative value or quality of the two lives. This interpretation moves away from the specific medical details and frames the case as a wider application of the defence of necessity, where the 'evil' of killing Mary was considered lesser than the 'evil' of allowing both to die (Brooke LJ, p. 1073). This ratio could potentially be applied to other situations beyond conjoined twins, such as in resource allocation or emergency situations.
The Most Defensible Version
The narrow ratio is the most defensible interpretation. The judges, particularly Brooke LJ, repeatedly emphasised the uniqueness of the case, stating, "it is important that the law should not be thought to be authorising euthanasia" (p. 1075). They were clearly anxious to avoid creating a wide precedent that could justify killing in other circumstances, a principle firmly rejected in cases like R v Dudley and Stephens (1884) 14 QBD 273. The court went to great lengths to distinguish the facts from a straightforward case of murder by focusing on Mary’s lack of independent viability. Robert Walker LJ characterised the surgery as a positive act towards Jodie but an omission towards Mary—the withdrawal of the blood supply she received from her sister. A broad ratio would ignore these careful distinctions and create a dangerous principle that the law has consistently resisted.
Altering a Material Fact
Using the narrow ratio as the most defensible version, we can see how altering a key fact would change the outcome. If Mary, while still dependent on Jodie for survival, had a normally functioning brain and was a conscious individual, the court's decision would almost certainly have been different.
The court's justification relied heavily on Mary’s non-viability and lack of conscious awareness. She was described as existing only as a "living organism" (Ward LJ, p. 1002). If Mary had a conscious existence, her right to life would be of equal weight to Jodie’s. The operation could no longer be framed as the withdrawal of support from a non-sentient being; it would be the active killing of a person with awareness and a right to life, in order to save another. The balancing exercise performed by the court would fail. The principle that one cannot choose between two lives, killing one to save the other, would apply. The defence of necessity would not be available, as the act would be a direct violation of the sanctity of life of a person with a recognised future, bringing the case squarely in line with the prohibition against killing established in Dudley and Stephens. Therefore, the court would likely have refused to grant the declaration, and the operation would have been unlawful.
References
Re A (conjoined twins: surgical separation) [2000] 4 All ER 961
R v Dudley and Stephens (1884) 14 QBD 273 DC
