The government's proposals to reform the mental health systemhave provoked widespread dismay,reports Jeremy Laurance

The authoritarian instincts of the labour government were laid bare when it published its white paper Reforming the Mental Health Act in December 2000. Described as the biggest reform of mental health legislation for 40 years its emphasis on the dangers posed by people with mental problems alarmed users of the service, who felt it cast them as monsters, and psychiatrists who complained it would turn them into jailers.

Publication of the proposals provoked widespread dismay. The Royal College of Psychiatrists said it "gives the impression of a radical shift in balance towards social control" while the Mental Health Alliance, an umbrella group of more than 20 organisations, issued a "Charter for consensual treatment" setting out measures to reverse the rising trend of compulsion.

Ministers chose to ignore these protests and when the draft mental health bill was published in June 2002 the most controversial proposals for new powers to treat people compulsorily in the community and to detain those judged to be dangerous were unchanged. I will consider these in turn.

One theme recurs through the homicide inquiries over the past decade like a tolling bell. In case after case the final, lethal attack occurred after the mentally ill man (for it is almost always a man) had stopped taking his medication.

The government has decided that the problem of non-compliance must be confronted and that the way to do it is to extend the powers now available to doctors to administer treatment forcibly. The prime targets, according to Professor Louis Appleby, the mental health tsar, are the "revolving door" patients - those who are regularly admitted to hospital with a psychotic episode, stabilise, get discharged, and then stop taking their medication so they suffer another episode, have to be readmitted"and the cycle begins again.

They can be in a terrible state," Professor Appleby said. "The aim of this provision is to help those who slip through the net."

Under the present law, it is illegal to section and treat forcibly someone who is not ill. The psychiatrist has to wait until the patient becomes sufficiently disturbed to warrant their being taken back to hospital and treated. Under the proposed new care and treatment orders, the psychiatrist will be able to step in as soon as a patient stops taking their drugs, before they get ill. Some psychiatrists - mainly those in the inner cities - see the provision as a necessary and humane addition to their powers.

However the new proposals mean, in effect, that patients will be detained in the community, an idea about which many patients and professionals feel uncomfortable. In the past, patients have always been able to hold their heads high when they left hospital. Professionals fear that extending compulsion into the sanctuary of people's homes will undermine the bond of trust that is essential for effective treatment to take place. Mental health user groups warn that the new provisions will drive people away from services.

The Commons Health Select Committee spelt out these concerns when the idea of community treatment orders was first floated in the early 1990s. In its 1993 report on community care it warned there could be "no middle ground between compulsory detention and freedom in the community." Saying a patient was well enough to leave hospital but not well enough to live independently could be open to abuse.

The committee of MPs warned that it would be impossible for patients to consent to the arrangement because "consent under the threat of duress cannot be judged to be true consent". Removing the right of patients to refuse treatment, not only while they were in hospital but in the future after they had been released, "raises grave questions about the right the state has to control its citizens".

In summary, there must be serious doubt whether imposing a new law will improve compliance with treatment. Clamping down in an authoritarian way on a vulnerable group is both discriminatory and cannot guarantee that the tiny minority who become violent without their treatment will continue to take it.

When Michael Stone was convicted on October 4, 2001 of the murder of Lin and Megan Russell and the attempted murder of Josie Russell, there was widespread relief that a line had been drawn under one of the nastiest crimes of the last century.

But relief turned to outrage when it emerged that Stone, a man with severe personality disorder, had been turned away from a psychiatric clinic on the grounds that he was untreatable. The case raised a fundamental dilemma about mental illness. Are people like Michael Stone mad or bad? If mad they deserve care and treatment by psychiatrists but if they are bad, who should be responsible for them? Psychiatrists resist being cast as jailers.

John Mahoney, joint head of mental health policy at the health department, summed up the dilemma that they pose for policy makers. "People can't accept the distinction between mental illness and personality disorder. Some (with dangerous severe personality disorder) are very bright people - in the top 20 per cent for intelligence - yet they are also sadists and child killers. The public can't accept someone like that is sane. They insist they must be crazy to do something like kill a child."

Sane or not, ministers have decided that something must be done about this small group of people, estimated to number up to 2,500 in all, most already in prison or mental hospital. But professionals are wary.

The legal advice received by the government is that a person can be detained under the Mental Health Act if they are being treated. The issue then turns on what counts as treatment. Treatment must make a difference to a patient's condition. But would a small improvement count? Or what about stopping deterioration? If the latter then it could be legal to detain those patients who were improving or remaining stable while those who were deteriorating would have to be discharged on the grounds that they could not be treated. The absurdity of that outcome highlights the difficulty with the bill.

Psychiatrists have always made judgements about who is dangerous and - despite their protests - have always been involved as agents of social control. But their judgements are not infallible.

A paper in The Lancet last December - based on 23 published studies of dangerousness - concluded that to prevent a single violent act in a year, six psychiatric patients would have to be detained throughout the period. In a commentary, researchers noted: "The forecasting of dangerousness remains like that of the weather - accurate over a few days but impotent to state longer term outcome with any certainty"

The impossibility of predicting very rare events is not the only problem, however. If "high risk" patients are to be detained for the protection of the public rather than in their own best interests, then the key factor determining who is detained should be dangerousness rather than mental illness. But on that ground drunks or men who regularly beat their wives should be locked up. People with mental problems commit a very small proportion of all serious violence and the proposed detention of mentally ill people is therefore discriminatory. This proposal in the bill is therefore ethically as well as practically objectionable.