The UK and EU announced <a href="https://www.thenationalnews.com/world/uk-news/2023/02/26/rishi-sunak-to-meet-european-commission-president-for-northern-ireland-protocol-talks/" target="_blank">a hard-fought Brexit deal</a> on Monday that will now have to survive the high temperatures of British politics. Britain’s Prime Minister <a href="https://www.thenationalnews.com/tags/rishi-sunak/" target="_blank">Rishi Sunak</a> unveiled the so-called Windsor Framework with European Commission president Ursula von der Leyen during her visit to the UK. The aim is to simplify trade across the Irish Sea, but the issue has much deeper implications for Northern Ireland's peace and identity. Mr Sunak will have to convince right-wing MPs, including his predecessor <a href="https://www.thenationalnews.com/tags/boris-johnson/" target="_blank">Boris Johnson</a>, that concessions to the EU such as oversight by European judges do not cross their red lines. Ms von der Leyen has meanwhile agreed to cut back EU checks at Irish Sea ports, addressing British complaints that the rules are too strict. After two Brexit deals in 2019 and 2020 that failed to put an end to UK-EU wrangling, it remains to be seen whether this time will be different. The Northern Ireland Protocol signed in 2019 broke a long stalemate over the terms of Brexit, but it imposed trade checks that soon angered British MPs. Goods were checked in the north so they could travel freely to EU member the Republic of Ireland, avoiding a “hard” Irish border that could inflame sectarian violence. But many Conservative and Democratic Unionist Party MPs said the checks were excessive and loosened ties between Northern Ireland and the British mainland. The issue led to the collapse of the devolved government in Belfast and was described by EU diplomats as <a href="https://www.thenationalnews.com/world/europe/2023/01/05/germany-tells-britain-lets-move-on-from-brexit-with-northern-ireland-deal/" target="_blank">the “Achilles heel” of post-Brexit ties</a> with Britain. UK and EU negotiators worked for months on a revised protocol deal, eventually beating the deadline of April’s 25th anniversary of the Good Friday peace deal. The EU has agreed to what Britain calls a “green and red lane” system, in which goods merely heading for Northern Ireland are not checked. There will still be checks on “red lane” goods that are destined for the EU’s single market. In return, Mr Sunak has conceded that the European Court of Justice has the final say on EU rules applied in Northern Ireland. "The European Court of Justice is the sole and ultimate arbiter of EU law," Ms von der Leyen said. There will also be a mechanism for Northern Irish politicians to express a view on new EU rules, addressing what MPs have called a “democratic deficit”. The so-called "Stormont Brake" will allow the Northern Ireland Assembly to object to new EU rules, Mr Sunak said. Whether the deal will see Britain drop its threat to unilaterally scrap parts of the protocol remains unclear. A bill to override the protocol was passed by MPs last year but has yet to become law. On the face of it, yes. Mr Sunak has a majority in the House of Commons, and the opposition Labour Party has said it is willing to back a deal. However, this is not a mere question of numbers. Mr Sunak may not mathematically need the support of Northern Irish MPs, but many Tories have made clear that if the DUP is not on board, then neither are they. DUP leader Jeffrey Donaldson said the party would take its time to consider the detail of the pact. Leading Eurosceptic MP Mark Francois said it was a “practical reality” that if the DUP does not agree with the deal then “it is simply not going to fly”. The ECJ's role is likely to be particularly contentious. Another prominent player is Mr Johnson, who has said the threat of unilateral action should remain, and is widely thought to be manoeuvring for a possible comeback. Mr Sunak could still win a vote with Labour’s support, but it would make him look weak and expose Tory divisions over Brexit. The US is another interested party. Senior figures in Congress have warned of damage to the “special relationship” with Britain if it does not strike a deal with the EU. There are rumours that President <a href="https://www.thenationalnews.com/tags/joe-biden/" target="_blank">Joe Biden</a> — who often talks of his Irish heritage — could visit the island to mark the Good Friday Agreement anniversary in April.