Within the debate about the rise of costs in the German health system, the argument has put forth that patients' excessive demand for benefits is caused by the existence of a moral hazard problem. One way of influencing an insured person's consumer behaviour is the introduction of several copayment models. The first task of this work is to examine the role of moral hazard in an insured person's consumer demand for drugs. Empirical evidence of this phenomenon is a central aspect of this task. Furthermore, the question if copayment is a suitable means of control to reduce the exorbitant demand for drugs will be answered. The focus here lies on the criteria effectiveness of control, reconcilabilty with the welfare state and effectiveness in general.