Britain is moving to override parts of the Northern Ireland Protocol amid pressure from Stormont and hardline Brexiteers in the Conservative Party. Brussels will launch three separate lawsuits against Britain in retaliation.
The Brexit Bill, which has been accused of undermining the Good Friday Agreement, is at the centre of the dispute.
Here we tell you everything you need to know about the Protocol, how Boris Johnson wants to change it and whether or not the UK and EU are headed for a trade war.
What is the Northern Ireland Protocol?
It was a deal struck between the UK and the European Union that determined what the trade rules would be for Northern Ireland after Brexit.
Northern Ireland shares a land border with Ireland, which is an EU member, over which goods move freely because there are no checkpoints.
Given all sides were committed to keeping that land border open, London and Brussels agreed to having checks on goods moving to and from the UK mainland.
But that effectively created a customs border between two different parts of the UK - Northern Ireland and Great Britain - which has infuriated Unionists.
What is the latest news?
The Northern Ireland Protocol Bill passed its second reading on Monday night by 295 votes to 221, with 283 Conservative MPs out of 359 in total voting in favour of the bill. None voted against it, while another 76 did not vote.
Theresa May on Monday night branded the Government’s plans to rip up the Northern Ireland Protocol unlawful.
In a scathing Commons speech, the former prime minister said ripping up the Northern Ireland Protocol Bill would “diminish the standing of the UK in the eyes of the world” but fail to secure a long-term solution to the sea border problem.
The second reading was the first chance MPs had to vote on the proposals.
For a year and a half, negotiators for the European Commission and the UK have been debating how trade frictions created by the Protocol can be eased.
The talks are deeply technical with no easy answers as the UK pushes to protect the integrity of the Union and Brussels tries to maintain the integrity of the single market.
Liz Truss, the Foreign Secretary, announced earlier this month that the UK would bring forward legislation to unilaterally suspend parts of the protocol.
It comes after the DUP refused to enter into power sharing in Stormont with Sinn Fein after elections in May that made the supporters of Irish reunification the biggest political party in Northern Ireland for the very first time.
The DUP made its opposition to the Protocol central to its campaign and is blocking the restoration of the Northern Ireland Assembly until it is removed or replaced, which means the Executive cannot tackle problems such as the cost of living and healthcare.
So what’s the problem?
Unionists fear the Protocol is driving a wedge between Northern Ireland and the rest of the UK.
The DUP claims the checks are driving up the cost of living but this is disputed by other parties in Northern Ireland, which claim the country’s special status in the Single Market has shielded its economy.
The British Government argues that the Protocol is having a chilling effect on trade from the rest of the UK, which is Northern Ireland’s principle trading partner.
Supply chains are shifting to EU suppliers to avoid the extra checks, which London says is unacceptable trade diversion.
Boris Johnson has also said that the Protocol is undermining the Good Friday Agreement because it does not have the support of unionists.
This is hotly contested by supporters of the agreement who see it as mitigation against the consequences of Brexit.
What will the legislation try to solve?
UK ministers argue the proposal will try to resolve a number of issues which exist with the current Northern Ireland Protocol.
One is that goods travelling from Great Britain to Northern Ireland that will never then be moved into Ireland are still being hit with timely checks.
To get around that issue, the UK is proposing a “red” and “green” lane, with goods only on sale in Northern Ireland being in the latter, which would involve fewer checks.
Another is about the ultimate arbiter of disputes. Downing Street wants the UK courts, not the European Court of Justice, to oversee the system. The legislation is expected to propose the former.
There is also frustration that because of the EU’s state aid rules, that UK-wide VAT cuts announced on renewable energy products cannot be adopted in Northern Ireland. That will be changed.
What is Article 16 of the Protocol?
Article 16 is a safeguard clause in the protocol, which the UK or EU can trigger if they believe the Brexit rules in the province have caused “serious economic, societal or environmental difficulties” or a “diversion of trade”.
Haven’t we been here before?
Yes. The Government published the UK Internal Market Bill in 2020 during trade negotiation with Brussels.
The Internal Market Bill gave the ministers power to disapply parts of the Protocol in case trade talks with the EU failed. It was dropped when the trade negotiations finished successfully.
Lord Frost’s threats to trigger Article 16 of the Protocol were credited with bringing Brussels to the negotiating table over the treaty last year.
Brussels can be slow to negotiate and must have the support of all 27 of its member states.
The Government seems to believe that only threats to tear up the Protocol can motivate the EU to get talking and make concessions in what has been dubbed the “madman strategy”.
Will there be a deal or will it be a trade war?
The introduction of tariffs and other trade protection measures by either side would constitute the beginning of a trade war. Any trade war would likely exacerbate the cost of living crisis and impact Western unity against Russian aggression in Ukraine.
The political consequences of a trade war would be significant for both sides and it is likely that an eventual agreement would be reached before it came to that.
However, the nature of the issue will require significant concessions from either the EU or the UK and it awaits to be seen how any future arrangement will turn out.
This article is kept updated with the latest information.