The president of Europe's human rights court said on Thursday Britain had a legal obligation to comply with its injunctions after Prime Minister Rishi Sunak said he would ignore such orders over his plan to send some asylum seekers to Rwanda.
Under the scheme, asylum seekers who reach England's southern coast in small boats would be sent to the East African nation.
However, in June 2022, the ECtHR issued a last-minute injunction - known as interim measures under Rule 39 - to prevent the first deportations. Last November, the UK Supreme Court also ruled that the policy was unlawful because of failings in the Rwandan system.
To overcome this, a bill is going through the British parliament to declare Rwanda safe and give ministers power to decide whether to comply with injunctions from the ECtHR .
"There is a clear legal obligation under the convention for states to comply with Rule 39 measures," ECtHR president Siofra O’Leary told reporters in Strasbourg.
Where states had failed to comply with injunctions, issued "in exceptional circumstances where there is a real and imminent risk of irreparable harm", the court had ruled they had violated the European Convention on Human Rights, O'Leary said.
A spokesperson for Britain's Home Office, the ministry responsible for immigration policy, was not immediately able to comment.
Despite the legal setbacks, Sunak remains determined to put the Rwanda policy into operation amid pressure from right-wing lawmakers in his Conservative Party and, with an election expected this year, voter concern about thousands of asylum seekers arriving without permission across the Channel.
Almost 30,000 made the journey last year and Britain spends more than 3 billion pounds ($3.82 billion) a year processing asylum applications, with the cost of housing those awaiting a decision running about 8 million pounds a day.
Last week, lawmakers in parliament's lower House of Commons backed Sunak's "Safety of Rwanda Bill" which the government admits might not be compatible with the European Convention.
"I've been crystal clear, repeatedly, that I won't let a foreign court stop us from getting flights off, and getting this deterrent up and running," he said then.
O'Leary's comments are likely to anger Sunak's right-wing critics, some of whom want Britain to pull out of the convention altogether. They have already said have said his bill was not tough enough in ensuring judges could not block deportations.
However, the remarks might provide succour to critics of the bill. On Monday, parliament's upper house backed a largely symbolic motion to delay ratification of a new treaty with Rwanda and could seek to amend the bill when it comes before peers to consider it next week.
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