A seven-judge Supreme Court has begun hearing the appeal by terminally ill Marie Fleming against a High Court decision that she cannot be lawfully assisted in taking her own life at a time of her choice.
Ms Fleming, who suffers from multiple sclerosis, has a right to "a dignified death", her lawyer argued.
While agreeing Ms Fleming's claim can be described as asserting a constitutional right to commit suicide, her counsel Brian Murray said that is not a description that does full justice to her claim.
The exercise of a right to kill oneself gives exercise to the right of a person to determine the course of their own lives, including a right to decide the time and manner in which it will end, he said.
The State also has a strong interest in limiting that right in the interests of the common good, he agreed.
However, the particular circumstances of Ms Fleming, where she has reached a stage where her life is so undignified and so painful, means she has a right to a dignified death at a time and in a manner of her choice, he said.
He said she will physically further deteriorate and perhaps experience an increase in choking which she has found so distressing, will perhaps lose the limited movement of her head, may lose the ability to communicate and may be "locked in".
She may be faced with a painful death or a death after she becomes comatose and she knows she can do nothing about that.
A "cruel irony" is that, were she abled bodied and not experiencing the same acute degree of suffering, she would be able to take her own life, he said. She now regretted that she had not taken her own life at an earlier time when she was physically able to do so.
Ms Fleming (59) is in the final stages of multiple sclerosis and has said her long-term partner Tom Curran is willing to help her take her own life provided that is legally permissible.
A three-judge High Court ruled last month that the absolute ban on assisted suicide set out in Section 2.2 of the Criminal Law Suicide Act 1993 does not disproportionately infringe Ms Fleming's personal rights under the Constitution and is wholly justified in the public interest to protect vulnerable people.
The President of the High Court, Mr Justice Nicholas Kearns, Mr Justice Paul Carney and Mr Justice Gerard Hogan also ruled the Director of Public Prosecutions has no power to issue guidelines setting out what factors she would consider in deciding whether to prosecute cases of assisted suicide.
The court was however "sure" the Director of Public Prosecutions would adopt a humane and sensitive approach to Ms Fleming's plight, Mr Justice Kearns said.
Ms Fleming is not appealing against the court's decision that the DPP has no power to issue the guidelines sought.
Her appeal focuses on arguments the absolute ban on assisted suicide breaches her personal autonomy rights under the Constitution and European Convention on Human Rights and, in her particular circumstances, that breach is not justified on public interest grounds but is disproportionate and discriminatory.
The appeal continues.
