Access to organs for transplantation: overcoming "rejection".

Recent success in overcoming rejection of transplanted organs has led to a much greater demand for organs from donors and to a reconsideration of mechanisms for increasing the availability of organs from cadavers. In the latter respect the two basic systems are "contracting-in" and "contracting-out". Each system has different benefits and harms, and it is a value judgement that should be adopted. However, both systems raise legal, ethical and practical issues that must be addressed if organs for transplantation are to become available to all who need them.