Sir Ed Davey has recalled the "pain" of looking after his terminally ill mother when he was just a child as he called for more investment into palliative care.
The Lib Dem leader told the Politics Hub with Sophy Ridge that while he welcomed a debate on assisted dying, he is "quite sceptical" because of his own experience.
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Sir Ed's mother had bone cancer and secondary breast cancer "which is an extremely painful form of cancer", he said.
He was only 12 when she was diagnosed, and nursed her with his brother for three years at home before she died.
Describing the treatment she needed he said: "I would give her morphine every day as a teenager, helped give her self-injections, helped put pads on her to give herself electric shocks.
"I went through quite a lot of pain treatment. I saw my mother's reaction when she died and the pain left her face. So I was quite emotional.
"Linked with the whole issue around palliative care and having gone to hospices and seeing other people and talking to doctors, I genuinely think we can do far, far better than we've done in the past."
Sir Ed said he would "listen to the debate" on assisted dying "but I have to say, what I've done in the past, I've voted against, and I am quite sceptical."
The Kingston and Surbiton MP, who is now a carer for his disabled son, said he was also concerned about the "psychological impact" elderly or disabled people may feel about "being a burden on their loved ones", resulting in them agreeing to something that "actually in their heart of hearts they don't want to happen".
While the legislation currently being tabled relates to terminal illness only, he pointed to other countries with euthanasia laws, like Canada, where the qualifying criteria has broadened over time.
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The assisted dying bill, proposed by Kim Leadbeater, states that it would "allow adults who are terminally ill, subject to safeguards and protections, to request and be provided with assistance to end their own life".
The Labour MP has denied it would lead to a "slippery slope" of widening criteria, saying that would not happen if the legislation is done properly.
Speaking to Sky News earlier this month, she said that people who are terminally ill in the UK and want to end their lives have three options at the moment - "suffering, Switzerland and suicide", and her proposed law was about giving them a choice.
Campaign group My Death, My Decision want the legislation to go further to cover those who might not be terminally ill but who are facing unbearable suffering.
The first debate and vote is scheduled for 29 November. If passed, it will go through line by line scrutiny with further votes in the Commons and Lords before any changes are made.
If MP vote against it at the first hurdle, as they did last time changes to the law were considered in 2015, that would prevent it going any further.