WASHINGTON — Top British officials confronted a dilemma last spring. Should they offer to help the United States prosecute two British nationals accused of abusing hostages as part of an Islamic State cell in Syria? Or would the conditions of their proposal scare off the Trump administration and worsen relations?
In an internal debate over the longstanding thorny legal issues surrounding terrorism prosecutions, the officials discussed whether to share evidence to prosecute the suspects, two members of the so-called Beatles whose gruesome hostage beheadings drew widespread attention five years ago. Britain routinely seeks assurances that the Justice Department will not pursue the death penalty, which Britain has abolished.
While career law-enforcement professionals would understand and expect that stance, the British ambassador, Kim Darroch, warned London that senior Trump appointees like Jeff Sessions, Jim Mattis and Mike Pompeo and their aides would react with “something close to outrage” — risking broader damage to the countries’ close alliance.
“They already feel that we are dumping on them a problem for which we should take responsibility,” Mr. Darroch wrote last May in a message that was part of a trove of private negotiations and internal deliberations made public on Friday as part of a court ruling in London.
Mr. Darroch added, referring to Prime Minister Theresa May as P.M.: “They have been signaling to us for weeks now that we are in no position to attach any conditions to this. At best they will think we have tin ears. At worst, they will wind the president up to complain to the P.M. and, potentially, to hold a grudge.”
The next month, the British relented and told Mr. Sessions, then the attorney general, that he could have the evidence even if prosecutors sought to execute the two British nationals. But they still insisted that the suspects be prosecuted in a civilian courtroom, not by the military commissions system at the American wartime prison at Guantánamo Bay, Cuba.
A lawsuit challenging that decision was filed by the mother of El Shafee Elsheikh, who along with Alexanda Kotey was captured by an American-backed Kurdish militia in Syria a year ago. While a British court sided with the British government on Friday, she is likely to appeal, so it may be months before the case is resolved.
Mr. Elsheikh and Mr. Kotey were half of a group of British members of ISIS suspected of imprisoning and beheading Western hostages, including four Americans and Britons. Their captives labeled them “the Beatles” for their accents. The leader of the group, known as Jihadi John, was killed in an American drone strike, while a fourth is imprisoned in Turkey.
The two are among hundreds of ISIS fighters held by the Kurds. The prisoners hail from dozens of countries, including many from Europe, that have been reluctant to repatriate them. The court ruling illustrates the problems facing many of those countries: The Americans got involved because British prosecutors decided the evidence was insufficient for charges under British law.
The United States has more expansive laws for incarcerating people who joined terrorism groups, including the offense of providing material support to a terrorist organization. It also operates the Guantánamo prison, where it holds several dozen terrorism suspects without charges and is trying to prosecute a handful through the troubled military commissions system.
Like many European allies, Britain strongly opposes the Guantánamo prison. Mrs. May’s government was afraid that the Trump administration might send the two British men there, a recurring theme in the ruling.
Last March, the ruling said, the British home secretary at the time, Amber Rudd, met with Mr. Sessions to discuss the case: “In the course of those discussions, he expressed the view that all foreign terrorist fighters should be prosecuted in their home countries. He referred to them as ‘prisoners of war,’ and to Guantánamo Bay as the appropriate place of detention for prisoners of war.”
After discussions with Justice Department officials in April, the British security minister, Ben Wallace, internally argued against pushing for assurances against the death penalty, saying that he had been warned that “there were strong voices arguing for Guantánamo” and that “the more restrictions the U.K. attached to support, the harder it would be to avoid that outcome.”
And on May 30, when the new British home secretary, Sajid Javid, met with Mr. Sessions, the attorney general said that “if the U.S. were to be willing to try Elsheikh in a civilian court as opposed to a military one, he could not see how the U.S. could do that without the U.K. evidence or without recourse to the death penalty.”
Ultimately, Mr. Javid told Mr. Sessions in June that the United States could have the evidence without death-penalty conditions, so long as it was not introduced in the military commissions system. That concession by the British appears to have persuaded senior Trump administration officials to focus on an eventual civilian trial in the Eastern District of Virginia on charges that would most likely include conspiracy in kidnapping resulting in death, an offense that carries the death penalty, according to officials familiar with internal deliberations.
Both Mr. Sessions, who was fired in November, and John R. Bolton, who became President Trump’s national security adviser in April, have agreed that a civilian trial is now seen as the most likely venue, according to former American officials. The family members of the victims had strongly pushed for that outcome. In a meeting with Mr. Bolton in late April, he was visibly emotional and pulled out a handkerchief in response to the families’ arguments, according to several people familiar with the meeting.
The British government immediately shared “a large number of witness statements” about the two men with the Justice Department, though testimony from British government officials would also probably be necessary at any trial. But after word of Mr. Javid’s move leaked to a British newspaper, Mr. Elsheikh’s mother filed the lawsuit.
Diane Foley, the mother of James Foley, whom ISIS beheaded in August 2014 in a video it posted for propaganda, said she was encouraged by the court’s ruling but suspected it would be months before the issue was resolved.
“The British are standing with us,” Ms. Foley said. “I think that it’s very important as a country we hold them accountable using our federal criminal courts so it can be an open, transparent process.”
Her son, a freelance journalist covering the civil war in Syria, was abducted in November 2012 along with a British photojournalist named John Cantlie, who has also been displayed in propaganda videos. Mr. Cantlie was thought late last year to still be alive but sick, according to officials familiar with intelligence about ISIS.