We are unsure whether Dr Wilson is suggesting that zero tolerance guidelines should not be applied to people who have a mental disorder or whether they should be abandoned altogether.

If the former, he perpetuates the stigma of mental illness and the public perception that psychiatrists are responsible for all actions of people receiving psychiatric treatment. Public attitude may affect people's volitional capacity (Reference Mele and RaddenMele, 2004). The view that all violent behaviour by users of mental health services is a manifestation of illness may therefore be anti-therapeutic by leading people to minimise their own sense of agency. If Dr Wilson is suggesting that the policy should be abandoned altogether, he is perpetuating the notion that people have unfettered rights to receive services. Our view is that this is not the case and that the rights of competent adults should be upheld in association with their observance of their duties.

Although we share Dr Wilson's concerns about the complexities of capacity assessments, ultimately it is these dichotomous judgements that determine whether people can consent to treatment, be allowed to take the consequences of self-harm or drug addiction and whether they go to jail or hospital for crimes they commit. If we reject the determinist stance that all actions by people with mental illness are undertaken because of their mental illness, it is hard to imagine a better way than by the assessment of their capacity to take responsibility for those actions in question.

Mental health workers, like prison officers, inevitably have to work with people who are aggressive and violent. It is appropriate that violence by prisoners should result in their freedom being further restricted. We believe that in addition to criminal prosecution, limiting or withdrawal of services may provide a similarly appropriate response to violence by capacitous users of mental health services.