A severely paralysed man is to ask the High Court for permission to allow doctors to help him die, after his wife refused because she said it would be very hard to live with the consequences.
Critics, including disability campaigners, say that any weakening of the law would endanger the lives of the vulnerable in society.
The man, known as Martin for legal reasons, had a severe stroke three years ago leaving him unable to move and only able to communicate using his eyes.
Last year the Crown Prosecution Service released guidance saying that people were unlikely to be prosecuted for assisting a suicide if they were “wholly motivated by compassion”.
Martin’s wife, known as Felicity, has refused to help her husband die so Martin is now seeking clarification in the law to ensure that medical staff or solicitors who help him die will avoid prosecution.
His wife, whose words were spoken by an actress, told the BBC: “I can understand his wish to die, but I find it very difficult to come to terms with that.
“I’m not prepared to help him. I would find that very hard to do and to live with the consequences, but I am prepared to be with him during the process to give him support and because I love him.”
Martin wants help dying by either refusing food and drink, or by travelling to Dignitas, the controversial Swiss suicide facility.
Martin said: “It is extremely important to me that I feel able to control when and how I die”.
He added: “As is no doubt appreciated, almost every other aspect of my life is now out of my control and I want, at least, to be able to control my death.
“I am clear that I no longer wish to continue to live and hope that people can respect this wish and now allow me to die. I want it over with without delay.”
Earlier this year a survey revealed that the majority of patients suffering from locked-in syndrome were happy and did not want to die.
The survey showed that the longer sufferers have the condition, the more likely they are to report happiness.
In March a father of three revealed that despite being severely paralysed by a stroke 21 years ago he has never wanted to end his life.
Kevin Weller has been unable to move or speak since he suffered the devastating stroke at the age of 32, but said he still feels happy.