It has prevented power sharing in the Stormont Assembly and has taken up hours of debating time in Westminster – but what is the Northern Ireland Protocol?
On Tuesday the Foreign Secretary Liz Truss set out the UK Government’s next steps on trying to solve the protracted issue of the protocol, which has caused difficulties for some political parties who disagree with it – such as the DUP.
There are plans to bring forward legislation within weeks overwriting parts of the post-Brexit deal.
The move was welcomed by DUP leader Sir Jeffrey Donaldson, who said “new and revised arrangements that are sensible” were needed.
The European Union Commission vice president Maros Sefcovic said any move to unilaterally override parts of the protocol raises “significant concerns”.
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.
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.
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 within 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 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.
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.
Foreign Secretary Liz Truss has confirmed she intends to introduce legislation “in the coming weeks” to make changes to the Northern Ireland Protocol.
In a statement to the House of Commons on Tuesday, Ms Truss said the bill would be introduced alongside “parallel” further talks with the European Union.
However, Ms Truss specifically said the government is not seeking to scrap the protocol.
Instead, her legislation will propose separate ‘green’ and ‘red’ lanes for goods travelling between Great Britain and Northern Ireland, drawing a line between those destined to stay within the UK — which will be freed from EU-level checks — and those heading to the Republic of Ireland and beyond.
This will override current arrangements, whereby Northern Ireland is effectively kept in the EU’s single market for goods, with a border down the Irish Sea.