Multiple sclerosis sufferer Debbie Purdy will learn whether her fight to allow her husband to help her commit suicide has been successful.
She took her case to have the law clarified on assisted dying to the highest court in the land where a panel of five Law Lords will give their ruling.
They sit at the House of Lords where earlier in the month a measure to remove the threat of prosecution from those who go abroad to help a terminally-ill patient die was defeated by peers who preside over Parliamentary business.
The judgment also comes in the same month that the Royal College of Nursing declared it was dropping its opposition to assisted suicide and adopting a neutral stance.
At a hearing last month, the Law Lords were told that both Ms Purdy, 46, and her husband, Cuban violinist Omar Puente, wanted to know whether he is likely to be prosecuted and what criteria the Director of Public Prosecutions takes into account when deciding whether to bring a charge under the Suicide Act.
As many as 115 people from the UK have gone to the Swiss clinic, Dignitas, to die, but no-one has been prosecuted so far.
Lord Pannick QC, representing her, said if the law was clarified, she may be forced to end her life earlier than she planned because her husband would be unable to help her if she became totally dependent.
Ms Purdy, from Undercliffe, Bradford, West Yorkshire, who was diagnosed with MS in 1995, has so far failed to secure a definitive ruling on the issue at both the High Court and Court of Appeal.
Lord Pannick said: "If the risk of prosecution is sufficiently low, she can wait until the very last minute before travelling with her husband's assistance."
He said if the risk was high, she would have to go earlier while she was still fit enough to travel without assistance. "It is ironic that the policy designed to protect the sanctity of life will have the effect of shortening the life of terminally-ill persons such as Ms Purdy."
