The Guardian view on asylum and Northern Ireland: Rishi Sunak has sabotaged his own legacy | Editorial

The Windsor framework was Rishi Sunak’s first significant achievement as prime minister and will probably turn out to be the last. A deal to settle problems with the way that Boris Johnson’s Brexit withdrawal agreement applied to Northern Ireland was achieved by rejecting the former prime minister’s maverick, confrontational approach and embracing instead an ethos of diplomatic pragmatism.

But no sooner had Mr Sunak demonstrated the merit in honouring international treaties than he abandoned that method with regard to immigration policy. His pledge to “stop the boats” ferrying refugees across the Channel produced acts of parliament that defy the European convention on human rights, which happens also to be integral to the Good Friday agreement underpinning peace in Northern Ireland.

A migration policy flimsily conceived from a simple slogan, and from which the prime minister has made no political gain, is at odds with the one act of serious statecraft for which he might deserve some credit. The contradiction was brought into stark relief this week when a Belfast court ruled that sections of the 2023 Illegal Migration Act should not apply in Northern Ireland.

A principal function of the act is to remove any prospect of a successful asylum claim from the vast majority of people who arrive by “irregular” means. With a few very narrowly defined exceptions, any refugee who crosses the Channel in a small boat is disqualified from ever settling in the UK. This is meant to be a disincentive to making the journey, and a precursor to deportation to Rwanda.

The high court ruled this arrangement to be a form of discrimination and a breach of human rights guarantees that – even if withdrawn in Britain – are still extended to everyone in Northern Ireland under the Good Friday agreement, by way of the Brexit withdrawal agreement and the Windsor framework.

That is a cluster headache for Mr Sunak. It turns Northern Ireland into a potential zone of sanctuary for anyone who might be eligible for deportation to Rwanda. It implies good prospects for success of a legal challenge to the recently passed Rwanda Safety Act, since that law is auxiliary to the Illegal Migration Act and builds on the same human rights violations. And it confirms fears among Northern Ireland unionists that Brexit arrangements create a jurisdictional border in the Irish Sea, despite Downing Street assurances that no such schism would be felt.

Ministers were warned of exactly this scenario unfolding. Those concerns were brushed aside with the combination of arrogance and irresponsibility that is a trademark of the current government.

Now Mr Sunak says the Belfast ruling will be appealed and, in the meantime, deportations to Rwanda from Britain can go ahead as planned. That might technically be true, but the prime minister’s ambition to declare decisive victory over small boat crossings and advertise that triumph as evidence of governing competence in an election campaign have suffered yet another blow. It was never a plausible aim, because a policy that prioritised gestural defiance of international norms over legal practicality was ill-conceived from the start.

That is something Mr Sunak appeared to understand when he negotiated the Windsor framework. In choosing to forget that lesson, he has damaged Britain’s reputation as a country that abides by international law, and has squandered what prospects he had of a legacy worth remembering.