The most interesting part of the press conference between the UK prime minister and the European Commission president, Ursula von der Leyen, was probably what Rishi Sunak said about the deal including a “Stormont brake”, which will allow the Northern Ireland assembly to stop new EU single market rules from applying in the region. He said the agreement “safeguards sovereignty” for Northern Ireland as a result. It had been reported that the agreement – known as the Windsor framework – would give the Northern Ireland assembly a right to be consulted on new single market rules; but this goes further, because the assembly would be able to block new rules applying in Northern Ireland. Sunak said: The only EU law that applies in Northern Ireland under the framework is the minimum necessary to avoid a hard border with Ireland and allow Northern Ireland business to continue accessing the EU market. But I know many people in Northern Ireland are worried about being subject to changes in EU goods law. To address that, today’s agreement introduces a new Stormont brake. Many have called for Stormont to have a say over these laws, but the Stormont brake goes further and means that Stormont can in fact stop them from applying in Northern Ireland. This will establish a clear process for which the democratically elected assembly can pull an emergency brake for changes to EU goods rules that would have significant and lasting effects on everyday lives. If the brake is pulled, the UK government will have a veto. This feature of the deal – assuming Sunak has described it accurately, and that critics do not find a catch when they get to inspect the small print of the deal – will make it hard for the DUP to oppose the deal. That is because, for the brake to apply, power sharing at Stormont would have to be restored. That would require the DUP to allow the assembly to start sitting (by backing the election of a speaker) and to lift its boycott on participating in the power-sharing executive. The DUP has said it will only do this if it gets a deal it finds acceptable. If the DUP were to continue to boycott the executive, the “Stormont brake” would not apply. And the alternative would not be no protocol; it would be Northern Ireland still being in the single market but not having the veto as described by Sunak. Unlike the DUP, Sinn Féin is not ideologically opposed to Northern Ireland being subject to EU laws. Its main political goal is for Irish reunification, which would probably involve Northern Ireland fully rejoining the EU. Sinn Féin has broadly welcomed the deal. Mary Lou McDonald, its president, said: “We are now at a turning point and that is good news for business and wider society. People in the north want and deserve certainty and stability. The economic possibilities the protocol opens up must be seized to benefit people in the north.”