The policy of any organisation is a setting out of the purposes for which it exists - its mission statement. Governments spend money on mental health services and therefore need a coherent mission statement for the use and goals to which that money is put. Moreover, the consequences of mental illness pervade all aspects of a nation's existence. Therefore a mission statement is needed to tackle mental illness and its consequences, not only by developing and using specialist mental health services to best effect, but also by using other relevant organisations as appropriate.

Mental health policy is formulated at all levels from the community mental health team to the national government and thence to the World Health Organisation and the United Nations. Indeed national and international mental health policies have generally been led by local innovative best clinical practice. At local level, the policy of a community mental health team will identify the types of patients to which it seeks to provide a service, the channels through which referrals will be accepted, the type and nature of assessment and decision making about consequent interventions which will be used and a range of quality standards within which it will seek to operate. It may set out a set of desired goals in terms of the improvement in the health status of clients and the degree of consumer satisfaction it seeks to achieve. Some adverse consequences may be set out. For example, it may seek to minimise readmissions to hospital within a specified period of time or the frequency of violent or self-destructive behaviour on behalf of its clients.