Brussels is set to do away with rules making the first country in which a refugee arrives responsible for any asylum claim, in a major shake-up of its refugee system.

The plan will be set out in March, when the European Commission unveils its reforms of the so-called Dublin regulation rules on asylum. But what is the existing regulation, how did the system get into this mess and how will Brussels fix it?

What is the ‘Dublin regulation’?

Put simply, the Dublin regulation — or to give it its official title, Regulation (EU) No 604/2013 — decides which nation is responsible for processing a refugee’s asylum claim.

While it takes into account issues such as family ties and health, the main rule is clear: the first country of entry is, in general, supposed to deal with the claim.

The idea behind the rule was that responsibility would be decided quickly so that asylum seekers did not end up stuck in a game of bureaucratic ping pong between two member states.

How does it work?

If an asylum seeker turns up in, for example, the Netherlands, Dutch officials are allowed to check to see if he or she has been registered elsewhere in the EU. If it turns out that the asylum seeker had their fingerprints taken in, say, Spain, the Dutch authorities could issue a “transfer” request asking Madrid to receive and handle the asylum application.

Madrid could argue against accepting the claim but if there were clear evidence, such as fingerprints, it would be legally bound to do so.

What went wrong with the Dublin regulation during the refugee crisis?

First, the sheer number of arrivals concentrated in just one or two countries overwhelmed the system. Some 850,000 people poured into Greece during 2015 alone, with nearly another 200,000 arriving in Italy. The existing regulation was not devised with these kind of numbers in mind.

Second, Germany stopped using it. When Angela Merkel, the chancellor, opened her arms to refugees she did so via the Dublin regulation, forfeiting Germany’s right to send hundreds of thousands of Syrians who flowed into the country back to Italy or Greece.

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Was it just the crisis that hit the Dublin regulation?

No, it was already broken. Migrants knew about the rules and were unwilling to be fingerprinted by Italian or Greek authorities as it reduced their chances of being able to remain in other preferred destination countries.

This attitude was matched by Italian and Greek officials, who often had little desire to force migrants to register as it increased the chances of their becoming an Italian or Greek responsibility — according to officials in northern countries.

On top of this, member states did not bother to see through most transfers even after requesting them, because deporting someone is time consuming and expensive. As a result, only 16,000 of 76,000 transfer requests were carried during 2013, according to the Migration Policy Institute.

So how will the regulation change?

Other than the demise of the “first country of entry” principle, no one knows yet. The commission has said it will outline the changes to the existing regulation in March, alongside a package of other migration reforms. Until then, all options are on the table.

Officials have discussed basing the new system on a relocation quota — the floundering plan to share out 160,000 asylum seekers from Italy and Greece among the rest of the EU. Member states have provided places for only 4,237 asylum seekers so far, while barely 300 have actually been moved.

Last week Dimitris Avramopoulos, European commissioner for migration, hinted before a committee of MEPs that there would be more “solidarity” among member states, signalling the end to a few countries at the edge of Europe bearing the legal responsibility.

Why does this affect Britain?

While British politicians regularly bemoan diktats from Brussels, the UK is one of the keenest supporters of the Dublin regulation. A look at the statistics will tell you why: since 2003, its rules have allowed Britain to deport more than 12,000 asylum seekers to other countries in the EU. It is little surprise that James Brokenshire, the UK’s immigration minister, reiterated early last year that London was “fully committed to the system created by the Dublin regulation”.

Britain has the choice on whether to take part in the Dublin rules, but it is a one-sided one. If Britain were to opt out it would lose the benefits of its geographic isolation for enforcing a hard-nosed asylum policy.

Will the reforms work?

During the refugee crisis the EU has come up with a series of policies that worked well on paper but flopped in practice, notably the relocation mechanism. A renewed push on this policy would be the first step towards a federal asylum policy and would undoubtedly prove controversial with national capitals. But with the arrivals in Greece showing no signs of slowing, Europe’s leaders may have little choice.