The Supreme Court has begun hearing terminally ill woman Marie Fleming's right to die appeal.

Lawyers for the 59-year-old who is in the final stages of multiple sclerosis say the outright ban on assisted suicide means she faces a death that will be painful, humiliating and distressing.

The former UCD lecturer is not in court but her partner Tom Curran is at the hearing.

Opening the appeal, her barrister Brian Murray, SC, has said she does not want her death to be the culmination of her suffering. She wants to die peacefully at a time and in a manner of her own choosing.

Practically that would mean administering gas through a facemask or using a cannula in her arm which she would activate by shaking her head or through a blowing action.

Mr. Murray says she is not asking someone else to kill her but she does need assistance ending her life.

Claims of discrimination in the law

The 59-year-old is challenging the 1993 law that imposes an outright ban on assisted suicide, arguing that it is unconstitutional and incompatible with the European Convention on Human Rights.

7 judges including Chief Justice Susan Denham are hearing the appeal which is due to last 3 days.

It is a challenge to the High Court's finding that the existing law is for the public good and does not disproportionately interfere with her personal rights.

Her lawyers say it is a cruel irony that were Marie Fleming able-bodied and therefore not perhaps experiencing the same acute degree of suffering she would be able to end her life.

It is part of her case that this amounts to discrimination.

The court has heard she has expressed regret that she did not take her life before her illness incapacitated her.

Her lawyers say on an objective analysis the death she faces is horrifying and before her life is over she may end up locked in - sentient but no longer able to communicate.

Lawyers for the State will advance their arguments tomorrow.