report in today's New York Times about a major decision of the UK Supreme Court:
The British government must withhold key evidence from the United States for the trial of two Islamic State detainees because the Trump administration has not provided assurances that the men will not be executed, the British Supreme Court ruled on Wednesday.The opinions in Elgizouli v. Secretary of State for the Home Dep't,  UKSC 10 are closely reasoned, scholarly, and repeatedly eloquent. Lady Hale's brief opinion helpfully summarizes the court's rulings. Two questions were presented (¶ 3):
The detainees were half of a cell of four ISIS Britons who handled Western hostages — some of whom were eventually beheaded on propaganda videos — and whose victims nicknamed them the Beatles because of their accents. Captured by a Kurdish militia in Syria in early 2018, the detainees, El Shafee Elsheikh and Alexanda Kotey, are being held by the American military in Iraq.
The ruling in a lawsuit was a major setback for senior law-enforcement officials in both countries. The British government had stripped the two men of their citizenship and had agreed to share evidence about them for use in an American trial without assurances that they would not face capital punishment, even though Britain has abolished the death penalty.
(i) it is unlawful at common law for the Government to facilitate the carrying out of the death penalty in a foreign state, not only by deporting or removing a person from the United Kingdom to be tried in that state, but also by providing information which may be used by that state in the trial of a person who is not currently in the United Kingdom; (ii) the decision to provide such information, insofar as it consists of personal data within the meaning of the Data Protection Act 2018 (“the 2018 Act”), was unlawful under Part 3 of that Act.A majority held that the first question should be answered in the negative, but the court was unanimous that the UK's decision to assist the U.S. violated the 2018 Act. Those interested in the intersection of the common law and human rights law will find this case "must" reading.