Under the law as it stands, some people die in pain without the dignity they had hoped for. As a result, many believe the legal position on assisted dying fails doctors, patients and their loved ones alike. Margo MacDonald is both brave and right to raise this issue in the way she has. If the Victorians had a taboo about discussing sex, it has been replaced today by death. The Independent MSP has Parkinson's disease and says if her life became so unbearable that she wanted to end it, that should be her right. Suicide has not been illegal for more than four decades but the dilemma confronting Ms MacDonald and many with degenerative conditions is that by the time they want to end their own lives, they may no longer have the capacity to do so. Though the courts have taken an increasingly lenient and understanding approach in recent years to assisted suicide and voluntary euthanasia, the law can turn compassionate doctors and desperate relatives into criminals.

One alternative for law-abiding citizens is to end their lives abroad in a country where assisted dying is either legal or effectively decriminalised. The pioneering Scottish businesswoman, Elizabeth Rivers-Bulkeley, chose this path in 2006 when she took a lethal dose of barbiturates at Zurich clinic Dignitas. However, a private member's bill introduced by LibDem MSP Jeremy Purvis the same year to give terminally ill patients access to assisted suicide in Scotland failed to reach the statute book, as did Lord Joffe's bill in the House of Lords.

Opponents argue that suffering can be minimised through palliative care and that all intentional killing undermines respect for life. Not only faith leaders but other objectors argue such legislation could pressurise vulnerable people into asking to be "put down" and that ruthless relatives might seek to hasten death for selfish reasons. However, as Ms MacDonald suggests, the status quo is equally unsatisfactory. Palliative care, though improved, is not always effective. It is an open secret that many doctors hasten the deaths of patients in pain and misery under the guise of relieving their symptoms, a procedure known as "the double effect". But this is legally risky and places an unfair burden on practitioners. The situation also produces botched suicides and untold emotional trauma among mercy-killers, some of whom go on to take their own lives.

Medically assisted deaths could be transparent and regulated, including provision for independent experts to establish a patient's wishes and frame of mind. Paradoxically, they may prolong life, rather than forcing patients to take action while still capable of committing suicide. At present even living wills, in which patients express their desire not to receive life-saving treatments, can be overridden by doctors and relatives who think they know best. It is time the whole issue of end-of-life decision- making was put under the spotlight.