On Friday, MPs will debate and vote for the first time on whether terminally ill people have the right to end their lives.

If MPs vote in favor of euthanasia, it could bring significant changes to British society, as well as reforms around the death penalty, divorce, abortion and same-sex marriage.

MPs last voted on the highly sensitive issue nearly a decade ago, when they roundly rejected the idea. But it is difficult to predict how such a momentous debate will be handled in the Commons, which contains many first-time MPs and is free to vote on the matter.

Jane Butterworth wanted to choose to end her life. She had advanced endometrial cancer and was told she had less than six months to live.

She watched her husband die of liver cancer 30 years ago, and she didn't want to make the same mistake again. "It was a very difficult and traumatic death," she said.

Under the proposed new laws, people like Jane who have been told they have less than six months to live will be able to obtain drugs to end their lives, but only with the consent of two doctors and a High Court judge, who The judge will review the decision.

Jane wanted to die at home with her son and daughter by her side, but she knew that even if the bill did pass, this was unlikely as she only had a few months left to live.

"It left me with really bad choices," she said. "We should make things work for people so they have the opportunity to die well - a comfortable death."

But opponents of the bill worry that, among other things, legalizing assisted dying will put hidden pressures on those who qualify for it.

Becki Bruneau's cancer had spread to her lungs. She opposes any changes to the law.

"My biggest fear is that if I'm in a lot of pain like I was two years ago and I don't have anyone with me, I might make the wrong decision," she told us. "Bad decisions are irreversible. You're dead.

Her views stem in part from her religious beliefs, but also because the bill would pose a danger to people with disabilities or terminal illnesses.

This is an argument often made by opponents of the legislation, especially those with disabilities. They fear the proposed law would reduce the value of life for many vulnerable people.

Becky shared the same concerns. She said this would open the door for people who were subjected to coercive control or forced to end their lives prematurely.

"This law could lead to people seeing themselves as a burden and the easiest option is to take their own life. This is very concerning, especially when people are at their most vulnerable."

Proposed bill in England and Wales comes with safeguards that supporters say would make it the toughest rules in the world

But others fear that if approved, the law on euthanasia could subsequently become more lax, meaning more people could receive euthanasia.

Mark Blackwell suffers from Parkinson's disease and is cared for around the clock by his wife Epi. He is not eligible for euthanasia under the terms of the bill, but he remains concerned about the impact the law could have on people like him with progressive illnesses.

Parkinson's disease is not considered a terminal illness. This is a disease that affects specific parts of the brain, which are gradually damaged over the years.

Mark's illness means he can no longer speak, but he can have some communication by blinking his eyes.

Asked whether legalizing assisted dying would make him feel burdened and pressured to end his life, he said it would.

Mark and Eppie have been married for 45 years and she told us that caring for him until the end of his natural life was her way of showing her love for him.

"When we got married, we made a vow that would last for better or worse, in sickness and in health," Eppie said. "Love is unconditional."

Their views were again influenced by their Christian faith, but also, they said, by their professional experiences. Both worked in psychiatry and both had suicidal patients.

Religious groups who believe in the sanctity of human life, along with disability charities, form the backbone of opposition to the proposed legislation, but arguments against changing the law are couched in very secular terms.

For Mark and Eppie, the argument comes down to simply valuing life.

Friday's vote is just the latest attempt to introduce euthanasia - which was first debated in Parliament in 1936.

The current bill is called the Terminal Ill Adults (End of Life) Bill and was introduced by Labor MP Kim Leadbeater.

She topped MPs' votes, so her bill - known as a "private member's bill" - was the first to be considered and likely had the best chance of becoming law.

While the government remains neutral on the issue, allowing MPs to vote according to their own beliefs, ministers have come out in support or opposition to the bill.

For retired High Court judge Sir Nicholas Mostyn, the compassionate approach would have been to give him the option to end his life before his health deteriorated to the point where he could no longer carry out his day job.

Like Mark, he has been diagnosed with Parkinson's disease, but is not yet in the advanced stages of the disease.

"If you have Parkinson's disease, your end can be long and very unpleasant," he told BBC News. He supported the bill — even though it did not give him the right to end his life.

Symptoms of Parkinson's disease include uncontrollable shaking of body parts and slow movement. In the most advanced stages, patients may find themselves unable to move and speak.

Sir Nicholas and some patients with other debilitating illnesses that are not considered terminal illnesses want the bill changed to cover them.

For some critics, this was an important reason to vote no.

They worry that, now or in the future, the bill could be expanded to include people who are not terminally ill — which they say would pose a danger to people with disabilities.

The most commonly cited example is Canada, which opponents call an example of a so-called "slippery slope."

Legislation introduced in 2016 initially targeted only terminally ill people, but was expanded in 2021 to include those experiencing "unbearable suffering" due to irreversible illness or disability. A further extension has been postponed but will still be available to people with mental illness within three years.

Sir Nicholas said: "I just don't understand the moral argument that because I wish to exercise sovereignty over my own body I am somehow contributing to the 'slippery slope' of abusing those who don't actually want (to end them)" life). "

Friday's vote - if passed - would be just the start of a lengthy parliamentary process followed by weeks of scrutiny by committees of MPs, scrutinizing the legislation line by line.

The bill will then return to the House of Commons before a further vote in the House of Lords to amend it.

Even if members of Congress vote in favor of the bill, there's still a long way to go before these proposed changes become law.

But if they do, it will mark another major overhaul of the law, as our society has changed dramatically over the past 50 years.