Two locked-in syndrome sufferers who find their lives "undignified and intolerable" are to take their right-to-die pleas to the High Court on Tuesday.
Three judges in London will hear an action brought by Tony Nicklinson, 57, from Melksham, Wiltshire, who suffered a catastrophic stroke in 2005 while on a business trip to Athens, which left him paralysed below the neck and unable to speak.
Mr Nicklinson, who communicates by blinking or limited head movement, sums up his existence as "dull, miserable, demeaning, undignified and intolerable" and wants a doctor to be able to lawfully end his life.
Lord Justice Toulson, sitting with Mr Justice Royce and Mrs Justice Macur, will hear a further "landmark" judicial review action brought by a man who suffered a "massive" stroke three years ago at the age of 43.
The man, who cannot be named for legal reasons, but is referred to as Martin or AM, is unable to move, is able to communicate only by moving his eyes, requires constant care and is entirely dependent on others for every aspect of his life.
Mr Nicklinson is seeking a declaration that "it would not be unlawful on the grounds of necessity for Mr Nicklinson's GP, or another doctor, to terminate or assist the termination of Mr Nicklinson's life".
He will also be asking for a second declaration over his right to respect for private life under Article 8 of the Human Rights Convention.
The declaration sought is that the "current law of murder and/or of assisted suicide is incompatible with Mr Nicklinson's right to respect for private life under Article 8...in so far as it criminalises voluntary active euthanasia and/or assisted suicide".
He was given the go-ahead for his legal action to proceed by a judge at the High Court in March who rejected a Ministry of Justice move to have the case "struck out".
Mr Justice Charles heard argument that it was not for the courts to act, but Parliament.
In his ruling he said the underlying issues in the case "raise questions that have great social, ethical and religious significance and they are questions on which widely differing beliefs and views are held, often strongly".
Mr Nicklinson accepted that "what he is seeking to do is to change the existing understanding of the common law".
Before the stroke Mr Nicklinson, who has two grown-up daughters, was a "very active and outgoing man".
He describes having no "privacy or dignity left" and says that what he objects to is having his right to choose taken away from him.
In a court statement he says: "By all means protect the vulnerable; by vulnerable I mean those who cannot make decisions for themselves. Just don't include me. I am not vulnerable.
"I don't need help or protection from death or those who would help me.
"If the legal consequences were not so huge, ie life imprisonment, perhaps I could get someone to help me. As things stand, I can't get help.
"I am asking for my right to choose when and how to die to be respected."
He wants a doctor to be able to terminate his life, with his consent and with him making the decision with full mental capacity.
At a previous hearing his QC Paul Bowen said his case was that "an act of euthanasia or assisted suicide" was the only means "by which his suffering may be brought to an end and his fundamental common law rights of autonomy and dignity may be vindicated".
Mr Nicklinson recently joined Twitter, where his case and the issues surrounding it have attracted widespread interest from thousands of followers.
In the other case, Martin will challenge the director of public prosecution's policy on assisted suicide, which he argues is insufficiently clear and fails to have regard to someone in his position.
He is not requesting a change in the law, but is asking that the DPP amend his current guidance so that professionals would not face criminal and/or disciplinary action if they helped him end his life.
At a preliminary hearing in his action, Lord Justice Toulson described it as a "tragic" and "exceptional" case which raised "thorny legal and ethical issues".
He said Martin lives at home in a specially adapted room and spends virtually all of his time in bed.
He is looked after by his wife, to whom he is "very close", and a team of full-time carers.
Martin has a "strong" and "constant" wish to end his life, but is unable to take the necessary steps "unless others take them for him".
His wife did not wish to "play any part in hastening his death" and no other family member is willing to help him end his life.