On one hand, the practice of paying research subjects can be grounded in the obligation of society to encourage forms of social cooperation useful in meeting the essential needs of its members. Fulfillment of basic welfare needs includes the provision of medical care to ameliorate the effects of illness and injury. Because the development of generalizable medical knowledge enhances the capacity to meet basic medical needs, it is desirable for society to promote the conduct of clinical research. Payment of research subjects encourages individuals to participate in clinical studies, thereby promoting the timely development of medical knowl-edge. Since paying research subjects improves the capacity of society to provide effective medical care, it is useful in fulfilling society's obligation to meet the essential needs of its members. Moreover, comparison with other social practices suggests that payment of research subjects should not be re-stricted according to the degree of risk subjects may incur or the amount of payment they may be offered. First, we encourage persons to engage in other paid work functions that are socially beneficial but dangerous. For example, society encourages persons to work as fire fighters, police officers, and soldiers. If society is willing to pay persons to engage in these risky but socially beneficial activities, then consistency seems to require that they also be allowed to receive payments for partic-ipating in socially beneficial research involving serious risk. Second, society permits persons to be paid handsomely for engaging in dangerous work activ-ities, even when their performance is not essential to the welfare of society. For example, persons are permitted to work as race car drivers, test pilots, and trapeze artists. If we acknowledge the freedom of persons to receive substan-tial payments for engaging in these dangerous but nonessential activities, it seems appropriate to also permit per-sons to receive substantial payments to participate in clinical research that may ameliorate essential needs of members of society. 1 Thus, the moral interest in promoting the welfare of society supports the practice of paying research subjects. Moreover, it suggests a policy that does not restrict the degree of risk incurred or level of remuneration received by paid subjects.

On the other hand, the moral interests of subjects raise serious reservations about payment practices. Concerns have focused on the interest in exercising the capacity for autonomous choice and the interest in fair treatment. The first is captured in the principle of respect for personal autonomy. In the context of research, it requires that the consent of subjects be both adequately informed and voluntary. Concern about payment focuses on the voluntariness condition.