10/09/2015 05:37 BST | Updated 09/09/2016 06:12 BST

The Commons Must Balance the Wider Risks of the Assisted Dying Bill

It is over a decade since Diane Pretty first challenged the legal position on assisted suicide. She was suffering from Motor Neurone Disease and wrote, "I want to have a quick death without suffering, at home surrounded by my family".

The question at the heart of the Assisted Dying Bill is whether we should now allow competent adults who are terminally ill to choose a medically assisted death without having to travel abroad to do so.

People who are able to make decisions for themselves already have the right to do so in all other aspects of their healthcare. Campaigners argue that to refuse access to assisted dying is to deny our fundamental right to self determination.

Parliament has a duty however, to balance the rights of the individual against the wider impact on others and to consider the unintended harms as well as the benefits.

The Bill would only allow a medically assisted death for those with a terminal illness who are judged to have less than six months to live. As drafted, it would not have applied for example to Tony Nicklinson, who also challenged the law after suffering a stroke in 2005 which left him with 'locked in' syndrome.

Capacity lies at the heart of this debate and, having crossed a line for those with less than six months to live, heart wrenching cases such as Mr Nicklinson's would inevitably lead to amendments. It would be an unsustainable position to deny the same rights to other mentally competent adults whose symptoms were intolerable to them. That line is liable to shift and blur because the tolerability of symptoms also depend on the individual and those around them. Many campaigners would of course welcome further amendments.

The scope of assisted dying has extended once legalised elsewhere, allowing for example, Swiss doctors to assist in ending the life of a healthy retired British nurse last year because she feared growing old. Across Europe the boundaries have extended to include children and conditions such as depression, thereby also biting into the core principles of capacity and informed consent.

How often in this debate do you hear the phrase that 'you wouldn't let your dog live like that'? Far from seeing this as an argument in favour of assisted dying, Parliament must take account of the unintended consequences of any slide towards a 'veterinary' approach to the value of human life. We should not dismiss the dangers of an attitudinal shift to society viewing it as cruel and unusual to keep some people alive. The very real concerns about attitudes to disability and the dangerous undercurrent of opinion that some lives are of lesser value must not be dismissed.

Depression and fear, including the dread of becoming a burden on loved ones, are a normal part of the painful adjustment to a terrible diagnosis. This often lasts far longer than the Bill's two week cooling off period. Whilst some argue that it is for individuals alone to decide if they want to make that journey, there is genuinely a risk that some will decide too early and particularly if they believe they are a burden on others. A right to die can start to feel like a duty to die.

A change in the law could have consequences for many other individuals and families if those weeks, months or even years are lost because of a decision taken at a time of hidden despair.

I know that distressing symptoms including the loss of dignity, are not always easy to control at the end of life but doctors are allowed to use the principle of double effect in order to control symptoms such as pain and breathlessness even if that has the effect of shortening life. There is a world of difference between this and doctors prescribing and supplying drugs with the sole purpose of deliberately ending their patients' lives; as a former GP I know that this Bill would profoundly change the relationship between patients and their doctors.

There is another problem in that the attending clinician would have to personally bring the drug to their patient and wait either in the same or the next room whilst it was self administered. In Oregon a lethal prescription is left with the patient for them to decide when to take it and many choose not do so at all. Under the proposals before the Commons however, the drug would have to be taken then and there or immediately be removed by the clinician. Picture the scene with family gathered and it is easy to see the risk that people will feel under pressure to commit to proceed; not so much a case of 'the doctor will see you now' as 'the doctor will help to kill you now'.

For all the Bill's supposed safeguards, once we cross the line to allow medically assisted dying we risk ending up in a very different place and with very different attitudes to the value of life. Far better in my view for Parliament to focus on the urgent need to improve palliative care. As reported by the Health Committee in March this year, access to specialist services at the end of life remains inadequate and unequal and there is far more we could do to make sure that people who wish to do so can remain at home at the end of their lives, including the provision of free social care. Conversations about prognosis need to start earlier so that wishes can be recorded and respected.

Should that support include the provision of drugs with the sole purpose of ending life? I fear that the wider harms outweigh the benefits and hope that Parliament will reject it.

Sarah Wollaston is the Conservative MP for Totnes and chairman of the House of Commons health select committee