A woman with multiple sclerosis has made legal history by winning her battle to have the law on assisted suicide clarified.
Debbie Purdy wanted to know if her husband would be prosecuted if he helped her end her life in Switzerland.
Five Law Lords ruled the Director of Public Prosecutions must specify when a person might face prosecution.
Ms Purdy, 46, from Bradford, said she was "ecstatic" at the ruling and she had been given her life back.
The Director of Public Prosecutions Keir Starmer said he would publish an interim policy on when prosecutions could occur by September before putting the issue out to public consultation. Permanent policy will be published next spring.
Ms Purdy said the Law Lords' decision was "a huge step towards a more compassionate law".
"I'm ecstatic - I feel like I've been given a reprieve.
"I want to live my life to the full but I don't want to suffer unnecessarily at the end of my life.
"The decision means that I can make an informed choice, with Omar, about whether he travels abroad with me to end my life because we will know exactly where we stand."
No one has been prosecuted for assisting someone's death, although the law says they could potentially face 14 years in prison.
The House of Lords, the highest court in the land, said the law was not as clear and precise as it should be.
Five Law Lords unanimously backed Ms Purdy's call for a policy statement from the Director of Public Prosecutions on when someone might face prosecution for helping a loved one end their life abroad.
Ms Purdy said she would like to see the policy distinguish between "what is acceptable and what isn't" so people in situations like hers could make decisions about what to do.
A spokesman from the Ministry of Justice said any change in the law was up to parliament.
"In a free vote on the issue on 7 July, the House of Lords rejected an attempt to decriminalise assisted suicide in circumstances where terminally ill people are helped to travel to countries where assisting dying is lawful," he said.
The Law Lords also said she had the right to choose how she died, under Article 8 of the European Convention on Human Rights.
In a summary of their decision, the Law Lords said: "Everyone has the right to respect for their private life and the way that Ms Purdy determines to spend the closing moments of her life is part of the act of living.
"Ms Purdy wishes to avoid an undignified and distressing end to her life. She is entitled to ask that this too must be respected."
She had previously lost challenges in the High Court and Court of Appeal. The Lords ruling was her last chance of success in the UK legal system.
Ms Purdy, married to Cuban violinist Omar Puente, was diagnosed with primary progressive MS in March 1995. She can no longer walk and is gradually losing strength in her upper body.
She has suggested that at some point she may travel to Switzerland to take a lethal dose of barbiturates prescribed by doctors at the controversial Dignitas organisation.
More than 100 UK citizens have so far ended their lives at Dignitas, and no-one who has accompanied them has ever been prosecuted on their return to the UK.
However, the reasons why legal action has not been taken have never been made clear.
Ms Purdy had previously said if the law was not clarified she would have had to end her life earlier than she wanted to.
Sarah Wootton, chief executive of Dignity in Dying, said: "This historic judgement ensures the law keeps up with changes in society and crucially, provides a more rational deterrent to abuse than a blanket ban which is never enforced.
"That must be better than the current legal muddle.
"The ruling is significant because it distinguishes between maliciously encouraging someone to commit suicide and compassionately supporting someone's decision to die."
Former Lord Chancellor, Lord Falconer, said it was a "very significant victory".
Simon Gillespie, chief executive of the MS Society, said: "There are 100,000 people with MS across the UK and most will live about as long as any of us.
"The key to living well with MS is getting the right care and support from the point of diagnosis, including palliative care when it's needed."
Attacking the decision, Phyllis Bowman, executive officer of Right To Life, said the group would be consulting its lawyers about what action it could take.
"Much as we sympathise with Ms Purdy, we are extremely concerned about the manner in which this will leave the vulnerable - that is the disabled, the sick, and the aged.
"Without exception, every disability rights group in the country, are completely opposed to any changing of the laws on assisted suicide and euthanasia."