The UK Supreme Court will rule Wednesday on whether a controversial government plan to send migrants to Rwanda is lawful, a decision with major political ramifications for Prime Minister Rishi Sunak.The Conservative leader says the scheme is crucial to reduce “illegal” immigration across the Channel on small boats — an issue set to feature prominently in the next general election.Five judges will announce their decision on the policy at 1000 GMT, after the government appealed a lower court judgement that it was unlawful.The ruling is the latest episode in a saga that began in April last year when Britain signed a deal with Rwanda to send undocumented migrants to interim centres in the African country. A favourable decision could boost Sunak’s chances of fending off the opposition Labour party in an election next year, but defeat would leave his immigration agenda in tatters. It could also widen rifts in the ruling Tory party between right-wing lawmakers and moderates.Hardliner Suella Braverman launched a scathing attack on the UK leader Tuesday, the day after she was fired as interior minister, accusing him of “betrayal” and “magical thinking” over the policy. She wants Britain to leave or disregard the European Court of Human Rights (ECHR) and “any other obligations which inhibit our ability to remove those with no right to be in the UK”. – ‘Stop the boats’ -The Migration and Economic Development Partnership envisages sending to Rwanda anyone who has made what the government calls “dangerous or illegal journeys, such as by small boat or hidden lorries” to the UK.The government insists it is essential to deter migrants trying to cross the Channel from northern France in rudimentary small vessels. More than 27,000 have made the journey this year.The government passed legislation in July barring any “illegal” arrivals from claiming asylum.Sunak’s pledge to “stop the boats” is one of his five key priorities for this year, after succeeding Liz Truss in October 2022.His administration says regular and irregular immigration must be slashed to ease pressure on housing and other social services, such as health. Opponents decry the Rwanda policy as cruel, expensive and difficult to implement. They also argue it is in breach of international law on asylum and refugees.The first deportees were on a plane and ready to fly to Rwanda in June 2022 when a last-minute ECHR injunction prevented any deportations.The Court of Appeal overturned in June an earlier High Court ruling that the plan was broadly lawful, prompting the Supreme Court case.- ‘Obsession’ -The appeal court judges decided that Rwanda was not a safe third country and there were risks that deportees could be sent to their home countries where they might be persecuted.A similar Supreme Court ruling will force the government back to the drawing board to try to drive down the numbers of asylum seekers. It is also expected to renew demands from right-wingers that Britain withdraw from the ECHR — a drastic idea that Sunak has so far refused to back. In her excoriating letter Braverman, who has called sending asylum seekers to Rwanda her “dream” and “obsession”, accused the prime minister of having “no appetite for doing what is necessary” on immigration.She is widely believed to covet the Tory leadership and her hardline stance on the issue is seen as red meat to the party’s grassroots. But Sunak’s surprise appointment of ex-prime minister David Cameron as foreign secretary and switch of James Cleverly to the interior ministry suggests he is halting his party’s post-Brexit lurch to the right.Chris Hopkins, politics director at polling firm Savanta, told AFP defeat in the Supreme Court “could highlight and increase” internal Tory divisions. Observers note that even a courtroom victory could be problematic, with potential challenges from individuals likely, the public unconvinced and time running out to implement it.”I think the jury will still be out whatever happens tomorrow,” added Hopkins.