ALEXANDA KOTEY and El Shafee Elsheikh are a long way from their west London homes. Like around 850 other Britons, they travelled to Syria to join the Islamic State when the terrorist group was at the height of its power. In Syria they gained notoriety as alleged members of the “Beatles”, a gang of four Britons who tortured and beheaded foreign hostages. As the caliphate collapsed, the two men were captured in January by the Syrian Democratic Forces, an American-backed militia, while trying to sneak into Turkey among refugees.

In a letter to Jeff Sessions, America’s attorney-general, sent on June 22nd and leaked this week to the Daily Telegraph, Sajid Javid, the home secretary, said that the British government did not want to try the two men, who have been stripped of their British citizenship. Instead, he said, the government would prefer the two men to be tried in America, because its tougher anti-terrorism laws make a conviction more likely. In the letter Mr Javid offered to share intelligence with the prosecution, without seeking the usual guarantee that the two would not face the death penalty if convicted. “There are strong reasons for not requiring a death penalty assurance in this specific case, so no such assurances will be sought,” he wrote.

News of the letter provoked surprise and, in some quarters, outrage. Ben Wallace, the minister for security, was hauled before Parliament by MPs, who demanded to know whether Britain had departed from its decades-old policy of not assisting prosecutions without assurances that the death penalty would not be used. Mr Wallace cited official guidance, in place since 2011, that in special cases assistance can in fact be provided even without such assurances, and suggested this may have happened before.

Mr Wallace’s remarks baffled many, who believed Britain’s strategy was to oppose the death penalty in all circumstances. Lord Carlile, the independent reviewer of terrorism legislation from 2001 to 2011, says he cannot think of a case like it during his tenure, and describes Mr Javid’s decision—made in secret and without public consultation—as “extraordinary”. Dominic Grieve, a former attorney-general who chairs Parliament’s security and intelligence committee, is also unaware of a precedent. Home Office sources hinted that Britain had previously helped with a handful of cases without death-penalty assurances, but declined to name them.

Either way, the case of Mr Kotey and Mr Elsheikh is the first to surface publicly. That puts the government in a tricky position. Not only does the episode undermine Britain’s opposition to executions overseas and its support for scrapping capital punishment worldwide. It also opens the government up to legal challenges. Mr Kotey and Mr Elsheikh could try to obtain a judicial review into why they were treated as an exception to a long-standing practice, in order to block their transfer to America. One group, the Howard League for Penal Reform, has already said that it is considering legal action.

Meanwhile, there is a squabble at home over who is responsible. Some argue that Mr Javid, who had been home secretary for less than two months at the time, made the wrong call. His allies say that the approach was agreed with Boris Johnson, then foreign secretary, and supported by Theresa May, a prime minister with six years at the Home Office under her belt.

Back in Parliament, Mr Wallace promised to find out when death-penalty assurances have not been sought in the past, and to pass the information to MPs. Given the murky nature of the episode, his findings may not satisfy those wondering whether Mr Javid’s letter was a rare exception, or a signal that Britain has discreetly softened its stance on capital punishment.