An assisted dying Bill claimed to be the “most robust” in the world has been unveiled as the Prime Minister insisted MPs must “make their own mind up” on the controversial issue.
Sir Keir indicated he is yet to decide on the proposed law, which is due to have its first debate at the end of the month.
It will be the first time assisted dying has been debated and voted on in the Commons in almost a decade.
Only terminally ill adults with less than six months to live who have a settled wish to end their lives would be eligible under the new law.
The Labour MP behind the Terminally Ill Adults (End of Life) Bill said hers is the only Bill in the world with “three layers of scrutiny” in the form of sign-off by two doctors and a High Court judge.
She said the proposed legislation for England and Wales would offer the “safest choice” for mentally competent adults at the end of their lives and is capable of protecting against coercion.
The Bill, which was published on Monday night, runs to almost 40 pages, with around 20 pages of explanatory notes.
Critics say the Bill is being “rushed with indecent haste” and that MPs will not have adequate time to scrutinise the legislation before the November 29 debate and vote.
But Ms Leadbeater rejected this argument, saying almost three weeks is “plenty of time to look at the Bill” and is normal within parliamentary timeframes.
She also suggested any new law would not take effect for another two to three years, with “even more consultation to make sure we get it right”.
She acknowledged this would be “heartbreaking” for people and families for whom change could come too late.
Sir Keir, who has previously supported assisted dying, said he will not pressure his MPs on the issue – on which the Government has pledged to remain neutral.
Asked if he is going to vote in favour of the legislation, the PM said: “Look, it’s going to be a free vote and I mean that. It will be for every MP to decide for themselves how they want to vote.
“I’m not going to be putting any pressure whatsoever on Labour MPs. They will make their own mind up, as I will be.
“Obviously a lot will depend on the detail and we need to get the balance right but I’ve always argued there will need to be proper safeguards in place.”
Ms Leadbeater said her private member’s bill would make it illegal for someone to persuade a person through dishonesty, coercion or pressure to declare they wanted to end their life or to induce someone to self-administer drugs to die.
Anyone found guilty of doing so would face a maximum prison sentence of 14 years.
In an interview with the PA news agency, Ms Leadbeater said: “Throughout the process there are layers and layers of safeguards and protections which I believe will probably make it the most robust piece of legislation in the world.”
It is thought the shortest timeframe for the process from first making a declaration to ending a life would be around a month.
Terminally ill people who have been resident in England and Wales for at least 12 months would have to take the prescribed medication themselves.
Health Secretary Wes Streeting has already said he intends to vote against the Bill, voicing his fears about coercion and people feeling a “duty to die”, while the Archbishop of Canterbury Justin Welby has warned of legalisation leading to a “slippery slope” in terms of who is eligible.
Justice Secretary Shabana Mahmood has previously stated she will oppose the Bill, saying she has has an “unshakeable belief in the sanctity and value of human life”.
High-profile supporters of a change in the law include Dame Esther Rantzen, who is terminally ill and revealed in December that she had joined Dignitas due to the current law.
The broadcaster has hailed the “wonderful” Bill, but acknowledged it would likely come into effect too late for her, and recognised its narrow criteria will not help people enduring unbearable pain and distress through chronic illness.
Ms Leadbeater said she has “consulted widely” on the Bill, speaking with medical and legal experts, disability rights activists, and many “with their own personal experience of why the current law is not fit for purpose”.
She said she had a responsibility to put before MPs “the best possible legislation and I believe I have done that”.
Rejecting the “slippery slope” argument around any widening of the legislation, she said: “I feel very confident that once this law is passed, that is where it will be and that is where it will stay.”
Right To Life UK branded the proposed legislation “a disaster in waiting”, and described the proposed measures as a “monumental change to our laws”.
Campaign group Our Duty Of Care, representing doctors and nurses, has sent a letter to the Prime Minister arguing it is “impossible for any government to draft assisted suicide laws which include protection from coercion and future expansion”.
