Supporters of right-to-die legislation are set to clash with top doctors, faith leaders and leading Anglican bishops in the House of Lords today.
The Archbishop of Canterbury, Dr Rowan Williams, is among those due to take part in a marathon Second Reading debate on the Assisted Dying for the Terminally Ill Bill, sponsored by crossbench peer Lord Joffe.
Dr Peter Saunders - Care, Not Killing
Lord Joffe says doctors should be able to prescribe drugs that a terminally-ill patient suffering terrible pain could take to end his or her own life.
But opponents say that if the Bill becomes law it could be open to abuse.
Dr Williams, Catholic Cardinal Cormac Murphy O'Connor and Chief Rabbi Sir Jonathan Sacks have written a letter to The Times in which they oppose any measure to legalise assisted suicide or euthanasia.
In the letter, they warn: "Such a Bill cannot guarantee that a right to die would not, for society's most vulnerable, become a duty to die."
A petition will be handed in at 10 Downing Street today signed by more than 100,000 people and demanding an end to attempts to change the law.
Care Not Killing, which represents more than 30 charities and health-care groups, is warning that the Joffe Bill would put the old and sick under intolerable pressure to end their lives, not least because of severe pressures on health and long-term care services.
Care Not Killing campaign director Dr Peter Saunders said: "We believe that this is a very bad Bill and one that would create great problems for old and sick patients and the medical and nursing professions.
"Over the past few days, as the public has become aware of the issues at stake, people have been signing our petition opposing the Bill at the rate of 10,000 a day."
Although peers do not by convention vote on the Second Reading of a Bill, Liberal Democrat QC and ex-MP Lord Carlile of Berriew - another opponent of the Bill - is expected to ask the House to back his "sunset clause" amendment.
PA