Voluntary patients entering mental health units retain the right to accept or refuse treatment, including ongoing admission, as they see fit. However the nature of acute mental distress means that some patients have fluctuations in their mental status and competency to make informed decisions. Inpatient mental health nurses face the ongoing challenge of practising in a way that balances the requirement to support and promote the autonomy of voluntary patients with the need, occasionally, to take actions which although they may appear paternalistic are needed to protect those patients or other people. Anecdotal evidence together with a clinical audit undertaken by the authors suggest that the practice of nurses requesting that doctors sign medical certificates which are then placed on patients' files 'just in case' they are needed has become a mechanism by which a minority of nurses deal with such challenges. A conceptual analysis of these issues indicates that such a practice is both legally questionable and ethically inappropriate. We suggest an alternative framework for practice that is legally and ethically preferable for both nurses and patients.