Why repeal and replace?
The Cabinet has agreed to hold a referendum on the Eighth Amendment, with ministers agreeing that voters should be asked whether or not to repeal the amendment, and also to replace it with new wording to be put into the Constitution.
It would state that the Oireachtas may provide for the termination of pregnancies in accordance with the law.
This decision was made following legal advice from the Attorney General.
Some people have called for a "repeal simpliciter", meaning simply repealing the Eighth Amendment.
However, the Government's advice, and the view of some experts, is that this could lead to complications.
Speaking on RTÉ's Morning Ireland, barrister Paul Anthony McDermott outlined some of the legal complexities.
The starting point is that the Constitution limits the right of the Oireachtas to legislate, for although we elect politicians and invite them to pass laws, they can't do whatever they like; they have to respect the fundamental rights in the Constitution.
In 1983, the Eighth Amendment expressly acknowledged the right to life of the unborn, and that is the provision that currently outlaws abortion save in exceptional circumstances.
The simple view is, if you take the Eighth Amendment out, problem solved, there's nothing in the Constitution restricting abortion, so the politicians are now free to legislate.
Where it becomes complicated is that, before 1983, a number of judges had made comments to suggest that abortion was outlawed by the Constitution even before the Eighth Amendment.
In other words, when Eamon De Valera was drafting it in 1937, it was a Constitution that was never intended to allow for abortion.
This comes from the idea of implied rights; that the Constitution contains some express rights, but also has implied rights, and so, for example, where it recognises the right to life generally, some judges have said that that must include the unborn.
The argument is that even if a repeal referendum passes and a Government passes legislation allowing for abortion, somebody could go to a court and say that legislation is still unconstitutional, because, even though the Eighth Amendment has now disappeared, that doesn't matter, abortion is still prohibited by the Constitution as a whole.
The idea is that by putting in a sentence such as "the Oireachtas may provide for the termination of pregnancy in accordance with law", that would make it harder for a judge to strike down the legislation.
The judge would look at that sentence and say it is clearly self-contained; it clearly says the Oireachtas can provide for this area, so it would be much harder for a judge to look at other parts of the Constitution and say that they still protect the rights of the unborn.
However, even with a replacement clause, any legislation could be open to legal challenge.
Even if a new law was passed, any citizen in Ireland could still go to the courts and argue the law is unconstitutional; that even if the Eighth Amendment was repealed, there are other provisions in the Constitution that protect the unborn. Judges have disagreed in the past as to whether it's right or wrong.
Suppose a hypothetical Government passed a law allowing for abortion up to six months or seven months, or eight months, and somebody brought that through the court. Could it be suggested that in those extreme circumstances, a judge would be unable to say it is unconstitutional and there was still somewhere in the Constitution rights protecting the unborn?
The argument will still be fought out before the courts. All this provision will do will be to make it easier for a judge to say no, the answer is clear, it's up to the Oireachtas and it can do what it likes.
Meaning of 'unborn'
In a further complication, in a High Court case in July 2016, Mr Justice Richard Humphreys, in the context of an immigration decision, suggested that the word unborn in the Constitution means more than protecting the right to life of the unborn.
He went on to say that the Children's Rights Referendum, which inserted a special provision in the Constitution to protect the rights of children, could also cover the unborn.
He was talking about that in the context of immigration and suggesting that if a parent or pregnant woman is about to be deported, that the unborn might have some rights in that scenario and might, for example, have a right to stay in Ireland.
There has never been a definitive Supreme Court decision on this and other judges have given different views.
The Government will be hoping the Supreme Court clarifies things very quickly.