Care Not Killing, an alliance of organisations campaigning against a change to the law on assisted suicide, has welcomed the High Court's rejection of another legal challenge this week.
Phil Newby, 49, who suffers from Motor Neurone Disease (MND), wants the law to be changed to allow people with incurable conditions to choose a "civilised ending".
Under current law in England and Wales, it remains illegal to encourage or assist a person in ending their own life, with anyone doing so facing a prison sentence of up to 14 years.
However, Mr Newby, from Rutland, lost his legal bid on Thursday. Delivering their verdict, the High Court judges concluded that the court was "not an appropriate forum for the discussion of the sanctity of life", the BBC reports.
Mr Newby has said he plans to appeal the decision.
Welcoming the verdict, Dr Gordon Macdonald, chief executive of Care Not Killing, said that changing the law on assisted suicide should be "a matter for Parliament, not for judges".
"This ruling recognises that Parliamentarians across the UK continue to reject attempts to introduce assisted suicide and euthanasia - more than a dozen times since 2003 - out of concern for public safety, including in 2015 when the House of Commons overwhelmingly voted against any change in the law by 330 votes to 118," he said.
"The current laws prohibiting assisted suicide and euthanasia do not need changing.
"It recognises the significant dangers of ripping up long held universal protections, that ensures the law treats all people equally and evidence from around the world confirms removing these protections puts vulnerable people at risk of abuse and of coming under pressure to end their lives prematurely."