Assessing decision-making and capacity in minimally-aware patients

The assessment of decision-making by minimally-aware patients represents an important challenge for medicine, science and the law. This paper seeks to assist the dialogue between these disciplines by discussing three aspects: the difficulties inherent in establishing a reliable means of communication with the patient; the difficulty of exploring understanding and decision-making once a means of communication has been determined; and the legal implications including problems that may arise with the 'balance of probabilities' legal standard of proof. These aspects are discussed using the example of patients who have very severe acquired brain damage or are in states which verge on the 'persistent vegetative state'. The discussion is informed by existing case law and by reference to clinical method and scientific theory including binomial theory.