Right-to-die campaigners, including the widow of Tony Nicklinson, remain optimistic that the law on assisted suicide will have to be discussed again by Parliament.
It was announced today that justices, considering whether the legal ban on assisted suicide is incompatible with the European Convention on Human Rights, had decided against them by a seven-two majority.
Jane Nicklinson, of Melksham, joined by Paul Lamb, a paralysed former builder from Leeds, had mounted the latest round of a legal challenge over decriminalising assisted suicide with a hearing at the Supreme Court in December.
Mr Nicklinson, who suffered locked-in syndrome after suffering a stroke, died aged 58 in August 2012 after starting the legal fight.
He lost a High Court battle to end his life with a doctor's help, and Mr Lamb won the right to join the litigation to continue the case.
Mrs Nicklinson said today: "I am disappointed that we lost. But it is a very positive step. Parliament will have to discuss this.
"I think Tony would be very pleased at how far we have come."
And Mr Lamb said: "I am very proud of myself. I know it is going to change."
Their solicitor, Saimo Chahal, said: "Whilst this is not exactly the result we were hoping for, and it does not provide an immediate remedy, it is nonetheless very welcome as we have succeeded in showing that the issue, despite the controversy surrounding it, is one that the courts can adjudicate on and indeed must, if Parliament does not take action soon to consider the plight of people like Paul.
"Jane and Paul can be very proud of the fact that they have made legal history in establishing what the courts should do when fundamental human rights are engaged, no matter how sensitive and difficult the moral and legal arguments are."
Lady Hale, deputy president of the Supreme Court, said today said it would not be beyond law makers to devise a process which identified the "few" who should be allowed to have assistance in dying without the fear that those involved could be prosecuted.
Making her comments in the Supreme Court ruling, she said the problem was ensuring that "vulnerable" people were not put under "undue pressures" to end their lives.
Lady Hale said that problem was not sufficient to justify a "universal ban" on assisting suicide.
But Andrea Williams, of Christian Concern, said of the ruling: "This is good news for the many vulnerable people who would have been at risk if the attempt to weaken the law on euthanasia and assisted suicide had been allowed by the Supreme Court.
"The murder law is there to set the highest priority on the importance and value of life and to protect it.
"While we have immense compassion for the Nicklinsons, Paul Lamb and 'Martin', their individual requests to end their lives by medical intervention would have been disproportionate to the safety of many.
"Parliament needs to continue to resist the repeated attempts by a small and determined lobby group to legalise assisted suicide.
"The issue has been comprehensively aired over many years in parliament and bills to introduce it have been resoundingly rejected.
"Parliament should continue to make clear the paramount importance of the protection and value of life for the most vulnerable in our society."