Families who help terminally ill relatives to end their lives will be free from the risk of prosecution after a landmark ruling yesterday.

The Director of Public Prosecutions is to rush out urgent guidance to clarify the law after Debbie Purdy, a multiple sclerosis sufferer, won an historic judgment from the House of Lords.

The guidance will not remove the offence of assisted suicide under the Suicide Act 1961 but make the situation clearer for people who help relatives to die in circumstances of “compassionate” assisted suicide.

In their unanimous ruling, five law lords said that the DPP must issue a “custom-built” policy stating the circumstances that would lead him to prosecute in such cases, and those where he would not. It is the first time that the DPP has been asked by the courts to detail the circumstances under which he would prosecute.

Keir Starmer, QC, the DPP, plans to issue temporary guidance within eight weeks and then draw up a draft prosecution policy for public consultation. A final policy statement would be published by next spring. “We have been handed a very big baton,” he told The Times. “This is extremely difficult and involves very sensitive issues. But we will run with it.”

Ms Purdy emerged from the House of Lords to cheers from supporters. She said that she was ecstatic. “It feels like everything else doesn’t matter and now I can just be a normal person,” she said. “It gives me my life back. I want to live my life to the full, but I don’t want to suffer unnecessarily at the end of my life. This 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. I am grateful to the law lords for listening and rising to the challenge that this case presented.”

Lord Pannick, QC, who represented Ms Purdy, said that he expected that the DPP’s guidance would ensure “that someone facing the appalling predicament of Ms Purdy would at least have the comfort of knowing that the spouse or friend who held their hand as they died would not end up in the dock at the Old Bailey”.

Ms Purdy’s solicitor, Saimo Chahal, from the law firm Bindmans, said: “It’s a fantastic victory and all the sweeter for the fact that it is a unanimous decision and the very last judgment of the House of Lords, which expands the ambit of Article 8 of the European Convention on Human Rights.”

In a statement after the ruling Mr Starmer said: “The CPS has great sympathy for the personal circumstances of Ms Purdy and her family. We will endeavour to produce an interim policy as quickly as possible which outlines the principal factors for and against prosecution. To that end, I have already set up a team to work through the summer with a view to producing an interim policy for prosecutors by the end of September. Once our interim policy is published, we will undertake a public consultation exercise in order to take account of the full range of views on this subject.”

To date, 115 people have travelled from Britain to a Swiss clinic to be helped to die. Eight cases have been referred to the DPP but no relatives have been prosecuted. However, the uncertainty has led some people to make their last journey alone, without family members, so as not to risk their being prosecuted, Lord Hope of Craighead, giving judgment yesterday, said. Others, he added, had given up the idea of assisted suicide and “been left to die what has been described as a distressing and undignified death”.

Sarah Wootton, chief executive of Dignity in Dying, said that the ruling would clear up “the current legal muddle”. She said: “A law which is not understood, enforced or supported by the majority of the public is not fit for purpose. The ruling distinguishes between maliciously encouraging someone to commit suicide and compassionately supporting someone’s decision to die, in order that these acts are treated differently. More and more people want choice about how they end their life. Yet, until now, the law has refused to say whether people would face prosecution for accompanying someone abroad to exercise this choice.”

This month, an amendment tabled by Lord Falconer of Thoroton to remove the threat of prosecution from those who go abroad to help the terminally ill to die was defeated by peers in the Lords sitting not as a court but as the second chamber of Parliament.

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