Motor neurone disease sufferer Noel Conway has lost his Court of Appeal challenge against a "blanket ban" on assisted dying.
The 68-year-old retired lecturer from Shrewsbury, who says he feels "entombed" by his illness, has fought a long legal battle for the right to a "peaceful and dignified" death.
He wanted help to die - which the law prevents - when he has less than six months left to live, still has the mental capacity to make the decision and has made a "voluntary, clear, settled and informed" decision.
He proposed that he could only receive assistance to die if a High Court judge determined that he met all three of those criteria.
Mr Conway challenged an earlier High Court rejection of his case at a hearing in May.
But his case was rejected on Wednesday by three senior judges - Master of the Rolls Sir Terence Etherton, Sir Brian Leveson and Lady Justice King.
Reading a summary of the ruling, Sir Terence said the court concluded it is not as well placed as Parliament to determine the "necessity and proportionality of a blanket ban".
He also said the High Court had evidence before it from which it could find that Mr Conway's proposed scheme was "inadequate to protect the weak and vulnerable" and failed to give enough weight to the "significance of the sanctity of life and to the scheme's potential to undermine trust and confidence as between doctors and patients".
Sir Terence added: "From the outset, we emphasise our great respect for him (Mr Conway) and for the dignity and courage which he has shown."
Mr Conway, who is supported by the campaign group Dignity in Dying, was too unwell to travel to London for the hearing.
He is now dependent on a ventilator for up to 23 hours a day and only has movement in his right hand, head and neck.
He cites his current options as to "effectively suffocate" by choosing to remove his ventilator or spend thousands travelling to Switzerland to end his life and have his family risk prosecution.
His appeal was opposed by the Secretary of State for Justice, with Humanists UK, Care Not Killing and Not Dead Yet UK also making submissions.