When two are born as one: the ethics of separating conjoined twins.

Conjoined twins pose a serious challenge to medical ethics because of the fact that most legally informed ethicists recognise the need to respect the sanctity of life principle for all children. This principle is not negated by impairments to a child nor by the fact that two children's fates may be so closely intertwined that what one does to one inevitably affects the other. Various mitigating factors enter clinical decisions such as the best interests of the child but these can appear rather strained in some of the more debated conjoined twins cases. We therefore need to evaluate the ethics of treatment for conjoined twins quite carefully so that significant ethical values and legal principles are not compromised or distorted beyond credibility. The idea of a potentiality principle that is close to but distinct from the substantial benefit principle as it is used in adult clinical decisions is mooted as one valuable tool in this area.