Pro-choice campaigners have said they are confident that the legalisation of abortion cannot be overturned by Stormont after the DUP threatened to use "every possible legal option" at its disposal.
Same-sex marriage and abortion became legal for the first time ever in Northern Ireland today. Secretary of State Julian Smith said the first gay marriage is expected to take place by Valentine's Day 2020.
He also plans for the new legal framework for access to abortion services here to be in place by March 31.
In the Assembly yesterday, DUP leader Arlene Foster said it wasn't the end of her party's efforts to oppose abortion here.
The DUP would explore "every possible legal option" open to it, she pledged.
A decision by Stormont Speaker Robin Newton not to suspend Assembly Rules to allow a last ditch attempt to stop abortion is expected to be challenged.
Sources said Attorney General John Larkin is likely to refer the Speaker's interpretation of the law on procedure to the Supreme Court.
If successful, that could open the door to the issue returning to Stormont soon. But Patrick Corrigan of Amnesty International said he believed there was nothing that could be done by the Assembly to overturn the liberalisation of the law. "This is a piece of Westminster legislation. The Assembly can pass whatever legislation it wants but it can't undermine or repeal Westminster law," he said.
"Given the extensive cross-party support for the new law in both the House of Commons and the Lords, I can't see that happening.
"There will be no appetite for repeal, particularly given that MPs know that the DUP would return Northern Ireland women to Victorian era legislation.
"We have had the UN Committee and the UK Supreme Court both indicating that Northern Ireland's abortion laws breached the UK state's obligation to uphold women's rights so I can't see Westminster wanting to take us back to 1861 law."
Speaking in the House of Commons yesterday, the Secretary of State acknowledged that Northern Ireland had entered a new era.
"We need to be clear that the law from tomorrow has changed across those two areas. Obviously we will hear the views of the Assembly and we will work with them but the law, from tomorrow, has changed," he said.
A last-minute effort to stop decriminalisation was blocked in the Assembly. Sinn Fein, Alliance, the Greens and People Before Profit boycotted the sitting. Unionist MLAs who oppose changing the law had signed a recall petition.
DUP MLA Paul Givan urged the suspension of standing orders to enable a private members' bill through in a single day to halt abortion reform.
However, Mr Newton said a new Speaker would need to be in place before the Assembly could consider such a legislative bid.
The election of a Speaker requires cross-community voting in the chamber - and such support was not forthcoming as the SDLP refused to back any appointment in the absence of a power-sharing executive.
The DUP had offered to support the SDLP's Patsy McGlone as the new speaker. But while strongly anti-abortion, he said he couldn't accept because it would mean "accepting no power-sharing Executive ... and turning on its head everything my party negotiated in the Good Friday Agreement".
Mr Newton said it was "not good practice" to take a piece of legislation through in one day.
"The Assembly cannot do any business until a Speaker and deputy speakers are elected," he said.
Mr Givan insisted that the Attorney General had indicated that standing orders could be suspended to allow the legislation to be considered.
Mr Newton maintained his stance, highlighting that he had received his own legal advice on the issue. As he was questioned by his own party's MLAs, the Speaker constantly received written guidance from his officials sitting beside him.
Mrs Foster said that Northern Ireland would now have one of the most liberal abortion regimes in Europe. She said it was a very sad and shameful day. "This is not a celebration day for the unborn," she added.
TUV leader Jim Allister said: "Until this moment, until this day in Northern Ireland, the safest place for an unborn child was in the sanctuary of its mother's womb. Sadly (now) the most dangerous place for some unborn will be in the mother's womb because the wanton decision can be taken to kill them."
But Sinn Fein deputy leader Michelle O'Neill said: "The DUP's stunt in the Assembly was pointless, and achieved nothing other than to bring the political institutions into further disrepute and further undermine public confidence.
"Sinn Fein welcomes the end of the denial of the right of our LGBT brothers and sisters to marry the person they love. Sinn Fein also welcomes the end of the archaic law criminalising women."
SDLP leader Colum Eastwood described the Assembly session as "a sham, stunt and joke" and it had been important to call it out.
UUP leader Robin Swann urged the Secretary of State to convene urgent all-party talks to see if there was any hope of saving the devolved institutions. He described proceedings yesterday as "a sad day for democracy in Northern Ireland and a sad day for the people of Northern Ireland". Alliance deputy leader Stephen Farry branded events in the chamber as a "complete and utter disgrace".