Next week, on 7 November, the Assisted Dying Bill will return to the Lords for scrutiny in committee. Lord Falconer's Bill to legalise assisted suicide was given its second reading in the House of Lords in June, and reports have it that opinion among their lordships appeared quite evenly balanced. By conven-tion, no vote was taken. Crucially, no wrecking amendment was intro-duced to derail the Bill, since its opponents recognised that it ought to be allowed a full airing in the lower, elected house - partly because of the level of popular support, and partly at the urging of the president of the Supreme Court.

While the Church of England is officially against legalisation, opinion within the Church is divided. In the run-up to June's debate, both Archbishop Desmond Tutu and Lord Carey came out in its support.

What is the issue, and what is the controversy about? The issue is whether terminally ill patients who want to end their lives may be helped to commit suicide. As things now stand, it is not illegal to commit suicide, but it is illegal to assist someone in so doing. That might sound odd and inconsistent, but it is not.

Suicide was decriminalised in 1961, not because Parliament decided that an individual's killing himself was a matter of public indifference, but because it recog-nised that prosecution and punish-ment were not the appropriate responses to a failed attempt at suicide. The appropriate response is the provision of psychiatric coun-selling. By declining to decrimin-alise assistance in suicide, however, Parliament has continued to affirm the norm that suicide is not to be encouraged.

Why is it controversial to make it legal to assist the suicide of the terminally ill? According to some of those in favour of it, the only reason it is controversial is because some people, most notably religious leaders, are so lacking in com-passion for the suffering of their fellow-humans that they are un- willing to compromise their rigid adherence to the principle of the sacredness (or absolute inviolability) of human life, claiming that only God has the right to take life.

For sure, there are some Christians who think this way, but I am not among them. If you are a pacifist, then you'll regard human life as something that a human should never take, no matter what the circumstances. But if you are not a pacifist (as I am not), then you'll admit that, though taking human life is an evil, it may sometimes be right - say, in self-defence, or in defence of the innocent against grave injustice.

Some non-pacifist Christians, alongside philosophical Kantians, nevertheless regard suicide as always and everywhere wrong, judging it to be invariably an expression of self-pity or despair in God. I don't agree. I can think of some cases of suicide that seem to me to be noble: for example, that of Henning von Tresckow, who, after learning of the failure of von Stauffenberg's plot to assassinate Hitler in July 1944, took himself out to no man's land on the Eastern Front, and blew himself up with hand grenades. Why? Because he feared that he would not be able to withstand the Gestapo's torture, and wanted to avoid betraying his fellow-conspirators. I find myself quite unable to condemn him for that. On the contrary, I admire him.

So while I do think that we are responsible for the handling of our lives before God, that our handling of them should be governed by moral law, and that we may not do with them exactly what we please, nevertheless I don't think that only God has the right to take human life. I think that we may take it responsibly.

Am I saying, therefore, that the case against the legalisation of assisted suicide has no grounds? Not at all. First, opposition does not come just from religious people; plenty of non-Christian parliament-arians and healthcare professionals oppose it. If that were not so, legalisation would have commanded majority support in the Royal Colleges of the medical professions and in Parliament a long time ago.

WHAT are the grounds for objecting? I see three main ones. First, there is reason to doubt the practical effectiveness of the safeguards that Lord Falconer's Bill proposes, in order to ensure that no one would suffer undue pressure from another person to choose an assisted death. The problem is that many vulnerable people live, make their choices, and exercise their "autonomy" in an environment that is hostile, not supportive.

In 2008 - before the full implications of the current financial and economic crisis had dawned on us - Julia Neuberger, writing in her book Not Dead Yet about the treatment of the elderly, reported that at any one time in the UK 500,000 elderly people are being abused, two-thirds of them at home by someone in a position of trust. Judging by the current home-page Action on Elder Abuse, nothing much has changed since. Moreover, in 2009 the Mid-Staffordshire Healthcare Trust scandal revealed that abuse of vulnerable patients extended to healthcare professionals.

Given such an actual social context, there is good reason to doubt that any set of procedures implemented by fallible and sinful human beings will suffice to ensure protection against hostile manipulation.

The second objection is that the legalisation of assisted suicide will enshrine in law the implicit endorsement of the principle that some life is not worth living, and is not to be borne. Once that is established, reasonable questions will then be raised about why the benefit of lethal relief should be confined to those capable of administering it themselves. Why deny it to those who need someone else to do it for them? Why not move from assisted suicide to voluntary euthanasia? And then, why restrict relief to the terminally ill? Indeed, why only to the physically ill? What about the chronically ill and the severely dis-abled? What about the chronically grief-stricken, those enduring the slow torture of life imprisonment, and the philosophically desperate?

It is notable that the Bill currently before Parliament, which would restrict eligibility to the terminally ill, would make no difference at all to most of the cases recently publicised by the media - not to Alzheimer's patients such as Terry Pratchett; nor to sufferers of multiple sclerosis such as Debbie Purdy; nor to quadriplegics such as the late Daniel James; nor to those subject to locked-in syndrome, such as the late Tony Nicklinson; nor to those unwilling to endure bereavement, such as the late Sir Edward Downes.

So the third objection follows from the second: once the principle is established in law that some life is not worth living and may be terminated, political momentum will gather for the extension of eligibility. We will move down the road taken by the Netherlands, where controversy continues over whether "unbearable suffering'" should include existential and psychological suffering as well as physical, and whether it should include those who are merely "tired of life".

Similar debates are being held in Belgium and Switzerland. Last year, for example, a Brussels doctor legally acceded to a request for a lethal injection by a 44-year-old whose sex-change operation to become a man had been botched. The same doctor had also overseen the euthanasia of 45-year-old congenitally deaf twins, who feared that they were going blind. Last summer in Switzerland, the Swiss Medical Association criticised the legal move by the organisation Exit to extend its assistance in suicide to elderly people who were not terminally ill, but were suffering from old age. And, in September, Belgium's justice minister approved the request for euthanasia of a convicted killer and rapist on the grounds that he was "suffering unbearably" from an incurable psychiatric condition.

SO THERE are three objections to the legalisation of assisted suicide for the terminally ill. Not the inviolability of human life, nor God's monopoly of the right to take it. Rather, the improbability of successfully ensuring the protection of those vulnerable to hostile manipulation; the logical implications of enshrining in law the principle that some life is not worth living; and the likely political momentum for the progressive relaxation of the conditions of eligibility.

But, if we don't allow assisted suicide, what can be done for those who are suffering grievously? In brief, three things. First, we can work to extend and deepen the national provision of palliative medicine and care, which continues to be very patchy. Second, in extreme cases we can offer palliative sedation to render a patient unconscious. And third, we can encourage doctors to administer whatever dose of pain-relieving drug is necessary, even at the risk of abbreviating life, by emphasising that there is no moral or legal objection, provided that the intention is to palliate, not to kill.

None of this, of course, will relieve those kinds of human suffering which don't consist of physical pain. It will do nothing for the deep weariness of the elderly, the chronic grief of the bereaved, or the profound frustrations of the life prisoner and the severely disabled.

The hard implication of this is that some kinds of suffering ought to be borne. But when suffering is borne for the sake of protecting fellow-citizens against the hostile manipulation that would arise from the legalisation of assisted suicide, then suffering is no longer mean-ingless for it becomes an act of love. And meaningful suffering is some-times easier to bear.

Professor Biggar is Regius Professor of Moral and Pastoral Theology, and Director of the McDonald Centre for Theology, Ethics, and Public Life, in the University of Oxford. He is the author of Aiming to Kill: The Ethics of Suicide and Euthanasia (DLT, 2004) and "The Road to Death on Demand", Standpoint magazine, March 2010: http://standpointmag.co.uk/text-march-10-the-road-to-death-on-demand-nigel-biggar-assisted-suicide