When EU leaders met in Dublin in June 1990, they could hardly have imagined that, three decades later, what they had agreed would threaten to tear the bloc apart.
At the Dublin Convention, the 12 members of the bloc - then known as the European Economic Community - agreed to rules about asylum applicants that would later become known as the Dublin Regulation.
The primary innovation, as it was viewed then, was that the country in which an asylum seeker first arrived would be responsible for processing them.
In other words, if a refugee landed in Italy, they would have to stay there.
This was particularly important ahead of the Maastricht Treaty, which in 1992 created EU citizenship and widened the scope of free movement within the bloc.
The Dublin Regulation has been updated several times since, but that core principle - known as the first-country-of-entry criteria - remained.
That became something of a problem as the EU faced a wave of migration crises over the past decade.
"If it all works well, then it's basically only countries on the outside, on the periphery of the European Union, that take in asylum seekers and then have to integrate them," Dr Jeroen Doomernik, who researches migration policy at the University of Amsterdam, told RTÉ News.
By most calculations, the Dublin Regulation has thus unfairly burdened the countries at the EU's southern borders, such as Greece and Italy.
And it encouraged people smugglers, who promised migrants that they could help them reach countries in the bloc with better resources.
With the far-right nipping at its heels, the EU has long promised to repeal the Dublin Regulation.
"I can announce that we will abolish the Dublin Regulation and we will replace it with a new European migration governance system," European Commission President Ursula von der Leyen said in her State of the Union address in 2020.
This week, the bloc finally agreed to do it, after years of negotiations. But, like many EU proposals, the original intention has been watered down.
On a technical basis, the Dublin Regulation will actually be replaced by the Asylum and Migration Management Regulation.
But the core principle - the first-country-of-entry criteria - remains.
"One part of the reform was an attempt to reform the Dublin Regulation, which is a dysfunctional piece of EU law," said Catherine Woollard, Director of the European Council on Refugees and Exiles.
"The problem is that the reform basically repeals the regulation and replaces it with a regulation that has the same rules."
When Ursula von der Leyen described migration as a European challenge that required a European solution, she was not being tongue in cheek.
But the European solution appears to be a plan to allow member states to offer financial compensation in lieu of accepting their fair share of migrants.
The hope, of course, is that most countries will agree to take in migrants.
The problem is that, while the EU has tentatively agreed on redistribution mechanisms in the past, they have never been fully implemented, and several countries have point-blank refused to participate.
"Unfortunately, we have not seen any consequences or any infringement proceedings for that. So this is something that needs to be seen - how they will really make sure that member states abide by the new rules," said Neda Noraie-Kia, the head of migration policy at the Heinrich Böll Foundation.
Rather than doing away with the principle of the Dublin Regulation, the main thrust of the new rules agreed will give those first-country-of-entry states stronger mechanisms to deal with asylum applicants.
"It means that Europeans will decide who comes to the EU and who can stay, not the smugglers. It means protecting those in need," Ms von der Leyen said.
By the EU's description, the New Pact on Migration and Asylum, as the new rules are formally known, will make it easier for member states to limit the number of migrants who enter the bloc.
Though full details of the deal have not been published, it's thought that it will also make it easier for countries to deport migrants whose asylum has been rejected.
The pact will do so in part by bolstering so-called border procedures, allowing an expanded use of detention.
That will see the creation of border-detention centres.
Human rights organisations believe this could prevent asylum applicants from gaining access to full and proper asylum procedures, a right that is enshrined in international law.
"One of the new grounds for detention, which means a legal reason to put somebody in detention, is in order to carry out a border procedure before allowing the person to enter the territory," said Ms Woollard.
"Large numbers of people will be contained at the borders in detention conditions. And, in those detention centres, the asylum procedures they have access to are likely to be second-rate procedures."
In some senses, the EU is formalising a practice that has long occurred at its borders.
Several countries have already resorted to detaining applicants before granting them the right to seek asylum.
Even then, now that detention is part and parcel of the approach, there is now some hope that the European Commission will take greater steps to combat its unlawful uses.
Under the plan, those new border procedures will form part of the EU's standard asylum regime.
But the pact also introduces three situations in which member states will actually be able to ignore many aspects of the law - known as derogatory regimes.
For instance, a member state can declare that it is in crisis due to a mass arrival of migrants, or has experienced a force majeure.
The primary concern is that these derogations will allow member states to delay registering an asylum application.
And that could allow pushbacks - meaning that countries could force migrants to leave their territory before they have gained access to asylum procedures.
"In that situation, they're not registered as an asylum applicant, so they can't have access to legal representation. It's like they're in a sort of black zone. And that is where an unlawful expulsion, violence against people, and summary removals are likely to be happening," said Ms Woollard.
Despite the criticisms, the agreement has put most member states, the European Commission, and the European Parliament - which was forced to make a series of concessions - on the same page.
And it remains to be seen how the pact will work in practice. It also still needs to be formally approved - something that is not likely to happen until the middle of next year.
One of the EU's stated goals has been to pursue an "ever-closer union".
The phrase does not have any legal basis - it is symbolic.
But, for the better part of a decade, the migration issue has threatened the core of that symbolism.
The hope is that what was agreed this week will stymy, or even reverse, that.
"That's why this is so complicated, because this is still a problem," said Dr Doomernik.
"Will we find solidarity in all of this? I think the proof of the pudding will be in the eating."
