Days after historic Assembly elections in Northern Ireland, the post-Brexit arrangements for the region are once again threatening to cause a serious clash between the UK and the EU.
Here are answers to some of the main questions.
– What is the protocol?
An arrangement governing trade across the Irish Sea post-Brexit. Negotiated between the UK and EU as part of the Withdrawal Agreement, it was how both sides overcame the main log-jam in the Brexit divorce talks – the Irish land border.
To avoid disrupting cross-border trade and a return of checkpoints along the politically sensitive frontier, London and Brussels essentially agreed to move new regulatory and customs processes to the Irish Sea.
That meant checks on trade between Great Britain and Northern Ireland, rather than on goods moving north and south within the island of Ireland.
Products shipped from Northern Ireland to Great Britain are largely unaffected by the protocol.
The red tape instead applies on movement in the other direction.
Since the start of 2021, a range of regulatory animal and plant safety checks have been in operation, including physical inspections of a proportion of freight arriving at Northern Ireland ports.
Customs declarations are also required for incoming commercial goods.
– How does the protocol work?
While the rest of the UK has left, Northern Ireland has remained in the EU single market for goods. The region must also apply EU customs rules at its ports, even though it is still part of the UK customs territory.
The protocol also sees Northern Ireland follow certain EU rules on state aid and VAT on goods.
Due to the extension of a “grace period” on a number of protocol provisions, some arrangements are not yet fully in force.
– Why is it so controversial?
The post-Brexit checks on goods moving from Great Britain to Northern Ireland are fiercely opposed by unionists and loyalists in Northern Ireland.
They argue that the creation of an “Irish Sea border” poses a threat to the place of Northern Ireland in the UK.
The protocol has been the subject of fierce criticism by unionists, prompting rallies and protests across the region in recent months.
It has also been challenged in court.
Not everyone in Northern Ireland opposes the protocol.
Businesses have taken issue with some of the fresh checks, but many also see a benefit in Northern Ireland having access to both UK and EU markets.
Sinn Fein, the SDLP and the Alliance Party say that while the protocol is not perfect and can be tweaked, it is the best way to insulate Northern Ireland from the impact of Brexit.
– What has it got to do with the Northern Ireland elections?
Voters in Northern Ireland went to the polls on May 5, with Sinn Fein emerging as the largest party with 27 seats.
The impasse and divisions of the Northern Ireland Protocol overshadowed the election campaign, with the DUP, led by Sir Jeffrey Donaldson, pledging not to enter the powersharing Executive until the issue of the protocol is solved.
The DUP had already pulled out of the Executive earlier this year ahead, citing opposition to the protocol.
The party lost a number of seats and saw its share of the vote fall.
The Alliance Party, which identifies as neither unionist nor nationalist, also had a very good election and surged to 17 seats – making in the third largest party in the Assembly.
The result means that a majority of MLAs in the Assembly support retaining the protocol.
It was a historic result, with a nationalist party emerging with the most seats for the first time.
Michelle O’Neill, the Sinn Fein leader in Northern Ireland, is in line to take the symbolic title of First Minister in the joint office of first and deputy first minister at the head of the Executive.
Sir Jeffrey, who would become deputy First Minister, has said that his party has a mandate not to enter the Executive until the UK Government addresses its concerns over the protocol, while also pointing out that every unionist elected to the Assembly opposes the protocol.
Parties in Northern Ireland have up to 24 weeks to nominate a First and deputy First Minister.
If they fail to do so, Northern Ireland could remain without a Government until the end of the year.
– What has the UK Government said?
The UK Government, alongside the EU, the Irish Government and the US administration, have urged the parties in Northern Ireland to form a powersharing Executive.
In the days since the Northern Ireland election, the UK Government has made clear that it is willing to imminently take unilateral action that would scrap or override parts of the protocol.
Attorney General Suella Braverman has issued legal advice that the UK could act because the EU’s implementation of the agreement was “disproportionate and unreasonable”.
Following a call with European Commission vice-president Maros Sefcovic on Thursday, a Foreign Office spokesman said Ms Truss made clear that the UK’s “overriding priority” is to protect peace and stability in Northern Ireland.
She told Mr Sefcovic the protocol has become “the greatest obstacle” to forming a new Northern Ireland Executive.
Sinn Fein has accused the UK Government of “pandering” to the DUP, while the Irish Government has said that it hopes a “landing zone” can be found between the UK and the EU.
– What would happen if the UK took action on the protocol?
Such a move would escalate the row between the UK and the EU, with warnings that it could result in a trade war.
On Thursday, Irish Foreign Affairs Minister Simon Coveney warned: “Clearly, if the UK breaches international law, if it undermines a protocol that is about protecting the integrity of the EU single market, then the EU can’t ignore that.”
In Northern Ireland, the DUP has indicated that it would return to the powersharing Executive if the Northern Ireland Protocol is resolved.
DUP MP Sammy Wilson has said his party has adopted a wait-and-see approach over what the UK Government will do about the Northern Ireland Protocol.
The Prime Minister also played down this week fears about a trade war.
Mr Johnson told BBC News: “Let’s face it, we’re talking about really, in the scheme of things, a very, very small part of the whole European economy and I think 0.4% of the value of the whole of the EU economy in Northern Ireland.
“It is crazy. I didn’t think there’s any need for drama. This is something that just needs to be fixed.”