Questions regarding the ages at which children and adolescents are likely to become capable of granting informed consent for medical or psychotherapeutic treatment provide new avenues for the interface between research in developmental psychology and applications in legal and health settings. An increasing emphasis upon voluntary choice and the active role of the individual in determining treatment outcomes has opened the way for greater consultation between health professionals and patients before, during, and after medical, dental, therapeutic, and psychiatric care. At the same time, advancement in the understanding of the benefits and risks associated with standard health procedures, together with the proliferation of alternative therapies, has meant that the range of treatment options open to patients has broadened immensely.
Dilemmas in the interface between law, health, and psychology
In keeping with innovations in health care, children's legal status has undergone dramatic change since the 1980s. In this respect, evidence on children's competency in legal settings has accumulated (see Cashmore and Bussey  for a review). These studies suggest that, under appropriate circumstances, even some children as young as 3 or 4 years can demonstrate their understanding of the distinction between truthfulness and lying in specialized domains of knowledge (Siegal and Peterson, 1996) and of the necessity for truthfulness in court (Peterson, 1991). When questioned in a manner that respects their assumptions about the purpose and relevance of conversations about the social world, even preschoolers can often resist misleading suggestions under cross examination (Newcombe and Siegal, 1997; Siegal et al., 1998).