British leaders love to talk about their “special relationship” with their American counterparts, but even the best relationship has its limits. One big question for Theresa May, Britain’s prime minister, as she visits Washington this week, is whether torture is beyond those limits or not.

When May meets President Trump at the White House on Friday, she will become the first world leader to hold a face-to-face meeting with him since his inauguration. For the prime minister, it’s an honor that comes at a crucial time; May is presenting the trip as a chance to strengthen transatlantic ties as a post-Brexit Britain begins to loosen its relationship with Europe.

Yet before May even began her journey across the Atlantic, the Trump administration had already complicated their meeting. A series of draft executive orders from the president’s orbit leaked to the press this week. Together, these drafts suggest that Trump is seeking to fulfill his most dramatic campaign pledges, from building a wall along the Mexican border to completely blocking the resettlement of Syrian refugees to the United States.

One particular draft order may be most worrying for Britons. Within this draft, the Trump administration appeared to call for a policy review that could potentially reopen the CIA’s notorious “black site” prisons used overseas — and also restart an interrogation program that critics describe as torture.

It remains unclear whether the draft order is a serious plan or whether it was floated to engage Trump’s base. Either way, the president himself has repeatedly expressed support for controversial interrogation techniques such as waterboarding, which he himself describes as torture. “We have to fight fire with fire,” Trump said during an interview with ABC News on Wednesday, explaining that unnamed intelligence officials had recently told him that torture “absolutely” works.

For May, this renewed discussion of torture is a problem. Officially, Britain opposes torture in the strongest terms. Its intelligence services are prohibited from handling any information gained through torture or other mistreatment. If the Trump administration were to actually reinstate measures that could be considered torture, Britain’s spy agencies might have to curtail their intelligence-sharing relationship.

Part of the problem is that it would be unclear what intelligence had been gleamed using these methods. “When you get a piece of intelligence it doesn’t come with a headline saying this intelligence was the product of waterboarding. You may well not know where the intelligence has come from,” Nigel Inkster, a former assistant chief and director of operations and intelligence at Britain’s foreign intelligence agency MI6, told Politico on Thursday.

The end result might be that British intelligence agencies would have to refuse all intelligence from the United States (a major blow to an agency like GCHQ, Britain’s equivalent of the National Security Agency, which works closely with its American counterpart) or run the risk of turning a blind eye to torture. Meanwhile, Britain would likely be forced to reconsider other aspects of its relationship with the United States as well, such as its extradition treaty.

So far, the prime minister has referred to the torture issue only in very cautious terms. During Wednesday’s Prime Minister’s Question Time, May was directly asked about Trump’s views of torture and offered a tepid response. “President Trump has repeatedly said that he will bring back torture as an instrument of policy,” said Andrew Tyrie, a member of her own Conservative Party. “When she sees him on Friday, will the prime minister make clear that in no circumstances will she permit Britain to be dragged into facilitating that torture, as we were after 11 September?”

“Our position on torture is clear: We do not sanction torture and do not get involved in it,” May responded. “That will continue to be our position.”

As she flew to the United States, May was quizzed again about torture by reporters on the plane. In another curt response, she seemed to admit that if Trump did move to allow torture, Britain would be forced to act. “Our guidance is very clear about the position … and our position has not changed,” the prime minister said when asked about the rules governing Britain’s intelligence agencies, according to the BBC.

In a speech Thursday afternoon at a retreat for senior Republicans in Philadelphia, May warned that the United States and Britain could not return to the “failed policies of the past,” though she did not mention torture directly.

The issue is especially anguishing for Britons because of the recent history of the transatlantic relationship. Despite initial denials, it eventually came to light that MI6 was involved in the CIA’s post-9/11 “secret rendition” program in which suspected extremists were abducted and in some cases tortured. The revelations caused widespread fallout within Britain’s intelligence community, and the legal repercussions continue to reverberate today: This month Britain’s top court decided that former foreign secretary Jack Straw could face trial alongside a former MI6 officer in one rendition case.

It remains unclear to what extent Britain’s intelligence services knew the full truth about the George W. Bush-era renditions, but in any future scenario they may have no such excuses.

There’s a broader worry for Britons, too. As lauded as the special relationship may be, many Britons believe that their government was too trusting of Washington in the aftermath of the 9/11 attacks and during the subsequent war on terror. Tony Blair, then the British prime minister, was derisively referred to as Bush’s “poodle” for his seemingly subservient attitude. Ahead of May’s meeting with Trump, human rights groups and politicians alike warned May not to make the same mistake.

That might sound easy. The pragmatic May is a very different politician from the populist Trump and surveys show that the majority of British citizens have a low opinion of the U.S. president anyway. But May is in a difficult position. Britain’s economy is suffering amid post-Brexit uncertainty and she needs to lay groundwork for a bilateral trade deal with Trump, a businessman who views himself as a skilled negotiator. Right now, she won’t want to rock that boat.

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