Tony Nicklinson, 56, communicates with the use of a Perspex board and letters, looking, blinking and nodding to spell out words.
He is seeking clarification on the law to make sure that if he asks his wife Jane, 54, to take direct action so he can die, she will not be prosecuted for murder and be given a mandatory life sentence.
Mr Nicklinson is unable to end his life without direct assistance - unless he starves and dehydrates himself to death.
His legal team wants a judicial review to clarify how the murder law applies in cases of mercy killing.
The proceedings come after new guidelines on assisted suicide were issued by Director of Public Prosecutions Keir Starmer in February.
The new guidelines put greater emphasis on the motivation of the suspect, meaning cases against those who act with compassion are unlikely to be pursued.
"Right-to-die" campaigner Debbie Purdy, who has multiple sclerosis, won a ruling from Law Lords to clarify the law.
But whereas her case would come under assisted suicide, because she would be able to take the final action to end her life, Mr Nicklinson's case would come under murder, meaning a loved one who helped directly end his life would be prosecuted for murder.
The lawyers will argue that the murder law does not have the flexibility to consider motivation and circumstance.
In a witness statement, Mr Nicklinson, from Chippenham, Wiltshire, said: "I am a 56-year-old man who suffered a catastrophic stroke in June 2005 whilst on a business trip to Athens, Greece.
"It left me paralysed below the neck and unable to speak. I need help in almost every aspect of my life. I cannot scratch if I itch. I cannot pick my nose if it is blocked and I can only eat if I am fed like a baby - only I won't grow out of it, unlike a baby.
"I have no privacy or dignity left. I am washed, dressed and put to bed by carers who are, after all, still strangers. I am fed-up with my life and don't want to spend the next 20 years or so like this.
"Am I grateful that the Athens doctors saved my life? No, I am not. If I had my time again, and knew then what I know now, I would have not called the ambulance but let nature take its course."
In a letter before claim, his law firm Bindman said: "If Jane Nicklinson, his wife, were to help her husband to end his life, she would have to take some positive steps that would put her at a very real risk of being prosecuted for murder, rather than assisted suicide, notwithstanding Tony Nicklinson's voluntary, clear, settled and informed decision to commit suicide at a future date. As you know, consent is no defence to murder.
"Mr and Mrs Nicklinson wish to know whether Mrs Nicklinson will be prosecuted for murder in the event that she were to assist her husband to end his life by taking active steps.
"There is, however, no guidance available setting out what factors you consider relevant in deciding whether it is in the public interest to bring a prosecution for murder in cases of 'mercy-killing' or euthanasia.
"We note the guidance that you have recently published setting out the factors that you consider relevant in deciding whether you will give your consent to a prosecution for assisted suicide under S 2(1) Suicide Act 1961.
"Among the factors that militate against a prosecution are that the victim has reached a voluntary, clear, settled and informed decision to commit suicide, and the suspect was wholly motivated by compassion.
"We understand that this guidance does not apply to cases of euthanasia or mercy-killing. However, we suggest that these factors are just as relevant to the decision to prosecute an individual for murder as they are to cases of assisted suicide."
Sarah Wootton, chief executive of Dignity in Dying, said: "Mr Nicklinson's situation is rare and tragic. His request to die presents society with difficult questions, for which there are no easy answers.
"One thing is clear: the current law fails Tony Nicklinson and his family.
"The law of murder is primarily used to convict people who act out of malicious motivation and as such carries a mandatory life sentence. It should not be used to prosecute someone who compassionately helps a person who is suffering to die at their request.
"The Law Commission established this as an area of concern in its 2006 review of murder law, calling for a further review into whether there should be a specific offence or defence of 'mercy killing'.
"In the absence of any review, we hope that this legal case will help to clarify the law as it applies to Mr Nicklinson and others, and put further pressure on the Government to address the problems with our existing and outdated murder law."
She continued: "This case raises many ethically difficult questions.
"It would be impossible not to feel sympathy for Mr Nicklinson and his family, yet we also understand that his right to control over his death must be balanced with concerns about the impact of legalising assisted suicide on potentially vulnerable groups.
"When working for social reform, there will always be a need to balance individual rights with the impact on society."
She added: "Decision-makers cannot bury their heads in the sand as if this is a theoretical problem. People are taking control at the end of their lives, often in desperate and dangerous ways.
"There is a difference between assisted dying for terminally ill people, assisted suicide for non-terminally ill people, 'mercy killing' and euthanasia, but the current law fails to reflect this."
The legal team will argue that the murder law interferes with Mr Nicklinson's right to respect for his private life under Article 8 of the European Convention on Human Rights (ECHR).
They will say he needs clarity on the how the law of murder applies in cases of genuine "mercy killing" so he can understand the implications for his wife.
And they will attempt to clarify the law to recognise the differences between genuine "mercy killing" and murder.
The lawyers said in their letter to the DPP: "We request that you issue policy guidance for prosecutors stating that even in cases of murder it will not always be in the public interest to prosecute, and that relevant factors against prosecution include that the 'victim' is over 18 years of age; has made a voluntary, clear, settled and informed decision to end their life; is unable by reason of their disability to commit suicide, even with assistance; and that the suspect is wholly motivated by compassion.
"Alternatively, if your policy is always to prosecute cases where the evidential threshold for murder has been crossed, we request that you confirm that to be the case and your reasons for adopting that policy."
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