The Assembly has sat for the first time in almost three years, amid attempts to prevent changes to abortion in Northern Ireland.
Members from the DUP and UUP were among those in attendance, while Sinn Féin did not participate, describing the sitting as a "circus".
The SDLP walked out of the chamber, with leader Colum Eastwood refusing to elect a new speaker, saying they "won't be party to a stunt which is using and abusing people's emotions over a sensitive issue".
He said: "There cannot be a unionist dominated talking shop, there cannot be a shadow assembly, there has to be a power-sharing assembly, a power-sharing executive, a North-South Ministerial Council. They are the fundamentals to which we will always hold dear.
We went into the chamber today to make it clear that the DUP who’ve been trying to do this for 40 years, will not railroad anybody into a shadow assembly that will be a talking shop, a unionist dominated talking shop. We will never, ever let that happen.
Mr Eastwood continued: "I would appeal after this stunt is over, I would appeal for the DUP, Sinn Féin, the British and Irish governments and all parties to get into a room and to begin to sort this problem out because there are many, many issues there that our people want dealt with.
"They will not be dealt with by political stunts or by pretending to be dealing with issues and using people’s emotions to do it."
Following the SDLP's walk-out, DUP leader Arlene Foster told the media: “We will continue to take legal advice in relation to this matter because it is such a critical matter for the lives of the unborn here in Northern Ireland.
“It appears that that legislation is going to come forward now by midnight tonight, that is not the end of the matter because we intend to look at our legal options in relation to the sitting there today, and of course if there were to be an assembly called back here it would be one of the first issues that we as a party would want to bring forward again.”
Sinn Féin vice president Michelle O’Neill said following the law-change deadline, her party would put forward a policy to see "harmonisation of law across this island" on abortion.
"We called this out for what it was last week whenever the DUP announced it that it was a day of political stunts, of antics - that’s been borne out by what we just witnessed in the assembly chamber," she commented.
"I wish the DUP and others put as much creativity into actually trying to make power-sharing work as they have done today to try and attempt to deny people their rights because that’s what today was about.”
The plenary session was due to begin on Monday morning but instead got underway at around 1pm, because of legal issues.
Northern Ireland’s Attorney General was seen at Stormont earlier. The DUP had consulted Mr Larkin on whether the assembly could debate the issue without electing a speaker and deputy speaker.
DUP MLA Paul Givan urged the suspension of standing orders to enable the bill to be considered.
However, outgoing speaker Robin Newton had taken his own legal advice and would not allow it. He said a new speaker would need to be in place before the Assembly could turn to such a legislative bid.
The election of a speaker requires cross-community backing in the chamber however nationalist members indicated they would not back the appointment.
Under the changes, same-sex marriages will be able to take place from January, while women will have greater access to terminations in the region from April.
Anti-abortion and pro-choice campaigners gathered at the front of Parliament Buildings on Monday morning to voice their contrasting views on the emotive Issue.
Sarah Ewart, who has become a vocal advocate for reform since having to travel to England for an abortion after receiving a diagnosis of fatal foetalabnormality, welcomed the decriminalisation.
"This law change will not fix what I had to go through but it will make ithopefully better for those who follow after me," she said.
Meanwhile anti-abortion activists held up placards stating that the decriminalisation was not in their name.
Activist Clive Johnston, from Strabane, warned of the consequences ofdecriminalisation, saying: "In today's world the most dangerous place to be is actually in the womb of a woman."
Monday’s lunchtime sitting was largely symbolic, as the Assembly cannot perform its legislative functions without a ministerial Executive in place.
The power-sharing institutions collapsed in January 2017 amid a row between the DUP and Sinn Féin - and despite numerous attempts to restore power, no consensus has been found.
MLAs who signed the 30-strong recall petition had insisted it will provide a forum to voice opposition to the imminent decriminalisation of abortion in Northern Ireland.
The proceedings ended after just under an hour. There had been a plan to bring MLAs back on Tuesday but the Ulster Unionists pulled their recall petition and so the Assembly on hiatus yet again.