MPs are due to vote next Friday on Kim Leadbeater’s bill to legalise assisted dying in England and Wales.About 100 MPs are thought to be undecided and the outcome of the vote is uncertain.Here are some of the key issues in the debate.The bill says only someone who has an “inevitably progressive illness, disease or medical condition which cannot be reversed by treatment” and whose death “can reasonably be expected within six months” will be eligible for an assisted death.Most doctors agree that it is difficult to predict with accuracy when someone will die from a terminal illness.

With cancer, prognosis is usually based on the type and stage of the disease, survival statistics, plus age and other health factors.Doctors usually give patients a range of time, but add that the person could die more quickly or live longer.Critics of assisted dying say doctors may feel under pressure to give a prognosis of which they cannot be certain.They point to cases where people have survived for months, sometimes years, beyond a given time range for the end of life.But some studies have shown that doctors are more often over-optimistic, meaning patients are more likely to die more quickly than expected.

The bill says that anyone who coerces or puts pressure on someone to have an assisted death will be liable to face a prison sentence of up to 14 years,This is to allay concerns that family members or friends could put pressure on sick and vulnerable people to choose an assisted death,Such concerns have been consistently raised by opponents of assisted dying,Wes Streeting, the health secretary and an opponent of assisted dying, said last month that he was “concerned about the risk of people being coerced into taking their own lives sooner than they would have liked, or feeling … guilt-tripped, feeling like a burden”,The penalty for this under the proposed law is severe.

But a big challenge is that coercion and pressure can be difficult to detect and hard to prove.The victim may not acknowledge the coercion.Charles Falconer, the former lord chancellor, has said the evidence from jurisdictions that have passed assisted dying laws “shows that these laws do not lead to cases of coercion”.Supporters of a change in the law say excellent palliative care must be provided alongside an assisted dying service in order to give terminally ill people genuine choice about the end of their life.Opponents say that if top-of-the-range palliative care is properly resourced, there is no need for an assisted dying law.

About 300,000 people were provided with palliative and end-of-life care in 200-plus hospices in 2022-23, according to Hospice UK.They cost £1.6bn a year to run, and only £500m comes from the government, with the remaining £1.1bn raised from donations, legacies, charity shops and other fundraising activities.One in five hospices have been forced to cut services in the past year or are planning to do so, the charity said in July.

Some are closing beds and making staff redundant.In some areas, there are state-of-the-art facilities; in other places, hospices are woefully under-resourced or cannot meet demand.Provision of specialist palliative care in hospitals and people’s homes is also uneven.An estimated 250-300 people a day die without the palliative care they need.And although palliative care can be first class, advocates of assisted dying say it cannot guarantee a pain-free death and does not offer control over timing.

There has been no proper study of the costs of providing an assisted dying service in England and Wales.Last week, Streeting triggered a row by ordering a review of potential costs, saying such a service could have an impact on other NHS provision.“Any new service comes at the expense of other competing pressures and priorities,” he said.But the Labour grandee Harriet Harman said such a review could “contaminate” the debate around assisted dying if it found that it was cheaper to the state than costly treatment and care.In Scotland, where the Holyrood parliament is also considering legalising assisted dying, the government has estimated the cost of such a service at between £263,434 and £313,882 in its first year, and increasing each year.

It said: “It is difficult to assess the accuracy of the estimated costs/savings … given the uncertainty around the likely number of cases and, in particular, how they will increase over time.”The costs include training healthcare professionals, providing administrative support and supplying medication.One analysis said three studies in the US and Canada showed assisted dying would reduce spending on healthcare and end-of-life care.In Switzerland, where assisted dying is provided privately, not by the state, an assisted death can cost more than £12,000.Dignitas, a non-profit organisation, says it offers reduced or even waived fees for people in “dire financial circumstances”.

About 300 million people around the world have access to some form of assisted dying,The proposed law before Westminster MPs is broadly in line with the Oregon model – the US state’s 1997 Death with Dignity Act – which restricts assisted dying to terminally ill, mentally competent adults with a life expectancy of six months or less,Oregon’s law, the basis of laws in many other jurisdictions, has not been widened in the past 27 years,Other jurisdictions have gone further,The Netherlands, Belgium and Luxembourg allow assisted dying in cases of an incurable condition or “unbearable suffering”.

In the Netherlands, this allowed a 29-year-old woman with psychiatric conditions to opt for an assisted death earlier this year.Canada, which legalised assisted dying in 2016, expanded its law after a court ruled in 2019 that restricting access to those who had a “reasonably foreseeable death” was unconstitutional.However, it has shelved plans to expand criteria to include people suffering solely from mental illnesses.Switzerland is the only jurisdiction that allows non-residents to travel to the country for an assisted death.Leadbeater’s bill stipulates that two doctors plus a high court judge must be satisfied that the choice of an assisted death is freely made by someone with the capacity to make that choice.

This is stricter than most laws around the world,The UK courts have made clear that it is for parliament to decide the scope of an assisted dying law,But some say a law could be subject to expansion by the courts via discrimination-based challenges under the European convention on human rights,The European court of human rights has never required a member state of the convention to extend its assisted dying regime,It has also said there is no right to die under the convention.

Some people are concerned that discussion on this crucial, complicated and controversial issue is being rushed.The vote due next Friday would come two and a half weeks after the details of the bill were published, and would follow five hours of debate in parliament.Others say public opinion backs legal change, the issues have been publicly aired and that it is time to test the mood in parliament almost a decade after MPs last voted.It is possible that the Commons debate next Friday may not end in a vote.If that is the case, the bill would be unlikely to progress.

If the vote is in favour of the bill, it will be scrutinised line by line by a committee and may be amended by the House of Lords or the House of Commons before a final vote.If the bill is voted down, it is very unlikely that the issue will return during this parliament.