NI’s Stormont Assembly will sit for the first time in nearly three years after being recalled in a last-ditch attempt to stop changes to the abortion law.
Unionist parties, who oppose the upcoming liberalisation, triggered the recall with a petition.
NI has been without a devolved government since January 2017 when the power-sharing parties split.
Abortion laws will change at midnight unless devolution is restored but the recall is seen as largely symbolic.
Without an executive in place, Stormont cannot affect the laws.
It is unlikely an executive will be established as it needs support from both the unionist and republican communities.
Why have politicians been recalled?
Stormont’s power-sharing government collapsed amid a bitter row between the Democratic Unionist Party (DUP) and Sinn Féin.
Several rounds of talks to restore the executive have not succeeded.
MPs in the House of Commons have since passed some key legislation for Northern Ireland.
In July, MPs voted for legislation which requires the government to liberalise abortion and extend same-sex marriage to Northern Ireland if devolution is not restored by 21 October.
The bid to recall the assembly was proposed by Northern Ireland peer Baroness O’Loan, who opposes any reform of the existing abortion law.
The petition was signed by 27 DUP assembly members, Ulster Unionist leader Robin Swann and his party colleagues Robbie Butler and Roy Beggs, as well as Traditional Unionist Voice (TUV) leader Jim Allister.
Proceedings in the assembly chamber are due to begin at 13:00 BST. They were previously due to start at 12:00 BST.
It is not clear if MLAs (members of the legislative assembly) will be able to debate the abortion law changes as they first have to elect a speaker with cross-community support.
What are the current rules on abortion in NI?
Northern Ireland’s abortion legislation is very different from the law in Great Britain.
The 1967 Abortion Act, which liberalised the rules in England, Scotland and Wales, was never extended to Northern Ireland.
Currently, a termination is only permitted in Northern Ireland if a woman’s life is at risk or if there is a risk of permanent and serious damage to her mental or physical health.
Rape, incest or diagnoses of fatal fetal abnormality – where medics believe that a baby will die before, during or shortly after birth – are not grounds for a legal abortion in Northern Ireland.
What positions are the parties taking?
Sinn Féin said the recall was merely “about playing to the gallery” and its MLAs would not go.
The SDLP did not sign the petition either but it has a number of MLAs who are opposed to abortion and are understood to be considering attending the recall sitting in spite of party leader Colum Eastwood branding the move a “stunt”.
The SDLP has described itself as a “pro-life party” but its politicians are free to vote with their conscience on abortion laws.
The DUP MLA Gordon Lyons said his party wanted to return to Stormont to “take decisions on issues that matter to the people of Northern Ireland”.
The Ulster Unionist Party said its 10 MLAs would go to the chamber and it has also proposed a second petition to recall the assembly on Tuesday.
The UUP’s Doug Beattie said his party’s petition was for MLAs to express anger about the collapse of devolution more than 1,000 days ago.
He denied the UUP was engaging in “stunt politics” of its own and said something needed to be done given the absence of formal talks to restore power-sharing at Stormont.
Alliance Party leader Naomi Long said none of her party’s MLAs would be attending and she described the recall as a “cynical political stunt”.
“The intention of this recall is not to block abortion law and equal marriage but to create the illusion the DUP are trying to do so,” she added.
The Green Party leader Clare Bailey said it was a “shameful pantomime” and that she would not enter the chamber.