In a landmark debate, politicians are due to discuss the right to die for the first time in almost 20 years today.
MPs will discuss the Assisted Dying Bill after it came top of the Private Members' Bill ballot after the General Election.
Lord Charles Falconer introduced legislation to the House of Lords last year but failed to secure enough time for a vote in Commons.
Speaking to BBC Radio 4's Today programme on Friday he said "the law has got to reflect what society wants."
Lord Charles Falconer
This will be the first key question of conscience for the new House of Commons.
Labour MP Rob Marris, who will introduce the bill, said the current law was a "mess" and said this new legislation was about offering people "choice and dignity".
MPs have a free vote on the issue.
The Press Association reports the Wolverhampton South West MP wrote in a blog: "With appropriate, strong safeguards, terminally ill adults of sound mind should be legally allowed to choose to have assistance to end their own lives.
"I value life, and I do understand that some people believe very deeply that ending one's own life is always wrong. Nevertheless, the depth and sincerity of their belief should not mean that they deny choice to those of us who do not share their beliefs."
The bill's clauses mean that two doctors and a High Court judge would have to satisfied of the requesting patient's eligibility - defined as being terminally ill with less than six months to live, mentally fit to make the decision and aware of alternatives - before the right to die would be allowed.
The bill would allow doctors to prescribe a lethal dose to terminally-ill patients judged to have six months or less to live and who request it.
The bill would only permit the patient to administer the medication to end their own life - so it would not allow euthanasia.
Labour MP Rob Marris introduced the Private Members' Bill
Marris added: "At present the law denies dying people the choice of a safe, legal assisted death, whilst turning a blind eye to home suicides, and to technically illegal actions by doctors, and to Dignitas deaths."
The contentious bill is due to create a stir both inside and outside Parliament. Prime Minister David Cameron is to miss the free vote as he attends regional visits.
A spokesman said: "The Prime Minister has made his views clear on this issue before. He is not convinced that further steps need to be taken and he is not in favour of an approach that would take us closer to euthanasia."
It has been 18 years since the last Commons vote on the right to die.
Earlier this month, the Archbishop of Canterbury warned the UK would cross a "legal and ethical Rubicon" if Parliament votes to let terminally ill patients end their lives, and urged MPs to reject plans to allow assisted suicide.
He joined many other religious leaders in condemning the bill, including Dr Shuja Shafi, secretary general of the Muslim Council of Britain, Ephraim Mirvis, chief rabbi of the United Hebrew Congregations of the Commonwealth and Lord Singh of Wimbledon, director of the Network of Sikh Organisations UK.