The publication of the South Devon Inquiry Report on Monday into the death of the social worker Georgina Robinson was merely the most recent to highlight the inadequate state of mental health services for people with severe mental illness. The Sou th Devon service is, however, a good deal better overall than most in the UK.

This is the first time I can remember during my career when the key players in the mental health field all agree on the overall strategy. The problem is not the policy but its implementation, which is struggling woefully.

Need for services may be four to five times as great in deprived urban areas as more affluent suburban and rural areas, and yet distribution of resources takes no account whatever of this. Furthermore, money is fixed largely in hospital-based care, whereas service users and their families want a 24-hour, reliable, year-round community-based service - at the moment, in most districts, community care "shuts up shop" outside office hours.

Patients want practical help and support, for example with housing, finance and employment, something to do during the day, and social relationships which give meaning to their lives. But at present they are often offered a monthly injection of drugs andlittle more.

Targeting of services is especially poor; many community psychiatric staff do not work with those with the most serious long-term problems; staffing of the services is dominated by health professionals (doctors, nurses); when what is required is an army of people to provide practical social care and help - people who are far less expensive to employ but who, with the right training and support, are able to provide a more flexible type of service.

Hospital beds are used extraordinarily inefficiently - many admissions could be avoided if there were good, round-the-clock care at home, which most patients prefer even when they are seriously ill. A high proportion of beds are occupied by people who nolonger need hospital care but do need long-term support.

There are two reasons for the catastrophic failure of community care implementation. Until these are tackled, avoidable tragedies will continue to shock, and tens of thousands of patients and their families will find the burden of mental illness unrelieved. The first is the dearth of visionary leadership and effective management in mental health services, accompanied by a lack of understanding by health and local authorities of the sheer enormity of the changes that have to be made in order to target the services at people with long-term serious mental illness.

The Government is aware of this and has recently, through the NHS Executive and Training Division, invested £100,000 in a joint initiative to launch a series of training events for managers in London. This programme and other similar initiatives are vital, but they alone will not bring about the management revolution the public has a right to demand.

The second important change must be to the legal framework for community care. The current Mental Health Act works against the possibility of caring effectively for patients in the community. The 1983 Act's underlying theme is that care and treatment forpeople who require compulsory care necessitates detention in hospital. It is obvious, however, that specific treatment, for example monthly medication, can be administered in one licensed place, perhaps a day centre or doctor's surgery, and the person obliged to live and be cared for elsewhere in a specified place, such as a supervised hostel, residential home or their own home.

The second philosophical flaw in the 1983 Act is the removal of medical treatment from the social context of care. The Act focuses not on patients but on doctors. Successful care from the patient's point of view, however, enables him or her to lead as normal a life in the community as possible. Other aspects of care and supervision - such as a good relationship with a key member of staff, a place to live, social opportunities and adequate financial support - are prerequisites of rehabilitation.

The radical transformation of mental health services over the past decade, from being hospital-based to community-focused, should surely now be reflected in legislation. The stigmatising notion that incarceration is a necessary precondition for effectivecare should be dropped. There will, of course, often be times when detention in a secure place is necessary in the interests of safety for the general public, and that place will frequently be a secure hospital ward. But there are many other patients who can be treated satisfactorily in their own homes or in hostels, group homes, registered care homes and so on.

Compulsory admission powers are used sparingly, and often very late in a relapse, because of the traumatic disruption to the patient's life and the disquieting sense of failure for the professionals involved in the event. Compulsory admission to hospitalshould surely be reserved for those patients whose conditions are unresponsive to treatment and who have a specific need for very safe or secure care.

The problems inherent in the 1983 Act affect the care of a wide range of seriously mentally disordered people, not just the small, seriously "at risk" group to which the patients at the centre of recent, well-publicised tragedies belong.

The principles on which a new mental health Act should be constructed should provide a more therapeutic framework for care, continue to control the unwarranted interventions of doctors, and yet provide more safety and security for patients, their families and the general public. Adopting these principles, one could devise a power for the compulsory care of seriously mentally disordered people.

This broader concept of a comprehensive care plan order, in which specific medical treatment could be given compulsorily only in the context of a wider plan of supervision and care, would protect patients' welfare, particularly while they were receiving medication against their wishes.

The time has come to jettison an Act which neither protects the public effectively nor provides the care which seriously mentally disordered people require to achieve a more fulfilled and happier life.

The author is a professor of psychology at the United Medical and Dental Schools of Guy's and St Thomas's hospitals.