As the Assisted Dying Bill goes through UK Parliament, a key proposed safeguard is that a patient must have the mental capacity to make the decision to end their life.

Dr Annabel Price works with terminally ill patients and is an author of an analysis of evidence presented to the Commission for Assisted Dying, which was published in BMC Medical Ethics today. She conducted  this research as a Clinical Lecturer in the Department of Psychological Medicine, King’s College London Institute of Psychiatry, but has recently moved to Cambridge as a Consultant in Liaison Psychiatry.

In this guest post she tells us about her work on this controversial topic, and how the Bill could be improved.

Mental capacity has been placed as a central safeguard in the new Assisted Dying Bill which is due to receive its second reading in the House of Lords in May 2014. The Bill is the fourth attempt in England and Wales in the past decade to pass assisted suicide legislation. It provides for a person who is terminally ill and has six months or less to live to seek and lawfully be provided with assistance to end their own life.

In order to be eligible for assisted suicide under the terms of the Bill a person must have the mental capacity to make the decision. The Bill does not explicitly define mental capacity but does construe it according to the Mental Capacity Act 2005. The Act came into force in 2007 and sets out criteria for a test of capacity. It aims to help clinicians to preserve patient autonomy for those who are able to make their own decisions and allow care to be provided in the best interests of those who lack this capacity.

As a psychiatrist working with people with terminal illness I developed an interest in the clinical, ethical and legal frameworks that surround assessment of those requesting assisted suicide. In 2008 I was involved in conducting a representative survey of the views of UK doctors across specialties on the legalisation of assisted suicide which found divided views, and those with religious beliefs and those who spent more time caring for the dying more opposed to legalisation. Another study looking at the same sample of doctors found that the majority thought that rational suicide was possible, even among the most religious, suggesting that this did not account for all opposition.

A key paper that influenced my decision to further study mental capacity assessment for patients requesting assisted suicide was a national survey of US forensic psychiatrists by Ganzini et al which found that those with views opposing assisted suicide advocated more stringent criteria for capacity determination. In 2009, I was fortunate enough to travel to Portland, Oregon, a US state where assisted suicide has been legalised for over a decade. I met Professor Ganzini and her colleagues and gained a fascinating insight into how assessing patients for assisted suicide works in clinical practice.

When the Commission on Assisted Dying was launched in 2010, I was invited along with Matthew Hotopf, Professor of General Hospital Psychiatry at King’s College London Institute of Psychiatry and senior author on this study to submit written and oral evidence. The experience of putting together and presenting the evidence helped me to clarify my thinking and articulate the challenges of assessing capacity in this group of patients. It also inspired me to explore the other experts’ perspectives on mental capacity and its assessment.

Our study, an in-depth analysis of the transcripts of evidence submitted to the Commission, showed that while most agreed about the importance of mental capacity as a central component of the proposed legislation, the concept of ‘mental capacity’ was inconsistent. There was no consensus amongst experts on what mental capacity is, what level of capacity is acceptable or how it should be assessed and there were varying interpretations of the use of the Mental Capacity Act with respect to assisted suicide.

The findings of this study reflect the broader conclusions of a recent report by the House of Lords Select Committee, published in March 2014 which was highly critical of how clinicians are applying the principles of the Mental Capacity Act in practice.

The challenge of defining mental capacity for assisted suicide and the standards and processes required for assessment should be a priority for debate. These standards and processes once defined should be integral to any assisted dying legislation.