A leaked letter from the British Home Secretary has sparked concerns Britain is ready to waive its longstanding objection to capital punishment.
Britain's government says it will not object to the United States seeking the death penalty for two accused British IS militants if they are extradited there.
The men are suspected of taking part in the kidnap, torture and murder of hostages.
Britain ceased executing prisoners in the 1960s and has long sought assurances from foreign governments that the death penalty would not be used in cases where it extradites suspects.
Britain has also long refused to provide evidence in any overseas trials for people it has extradited.
So does the latest news mean Britain’s stance is changing?
What’s the case about?
The suspected IS militants, Alexanda Kotey and El Shafee Elsheikh, were captured in Syria by US-backed forces in January and stripped of their British citizenship.
The US and UK have since been in discussions over how and where they should face justice.
The latest fork in the road comes after UK newspaper The Daily Telegraph leaked a letter from British Home Secretary Sajid Jayid to US Attorney General Jeff Sessions, saying Britain would not seek assurances against the men's execution.
“I am of the view that there are strong reasons for not requiring a death penalty assurance in this specific case, so no such assurances will be sought," the newspaper quotes Mr Jayid’s letter as saying.
The US has harsher charges for terrorism offences than those under UK law.
The suspected militants are believed to have belonged to a terror cell - nicknamed by other jihadists as "The Beatles" because of their British accents - which participated in the murder of Western hostages, including journalists.
One of the journalists was American James Foley.
His mother Diane said she does not support executing the accused.
"I am very against that. I think that would just make them martyrs in their twisted ideology. I would like them held accountable by being sent to prison for the rest of their lives,” she told the BBC.
What are people in Britain saying?
Critics of the decision are accusing the Home Secretary of hypocrisy and abandoning the country's long opposition to capital punishment.
Shadow Home Secretary Dianne Abbott has called for the decision to be reversed.
"In this case, the Home Secretary seems to have unilaterally ripped up those principles. What does he think principles mean? Isn’t what he's actually saying is that principle means nothing to the UK government anymore?,” the opposition Labour party's Yvette Cooper told parliament.
But Government Security Minister Ben Wallace said this is a special case.
"The crimes that we are talking about involve the beheading, and the videoing of those beheading, of dozens of innocent people by one of the most abhorrent organizations walking this earth,” he said.
“Simply to say, if we were unable to prosecute them in this country, that we should simply let them free to roam around the UK, is simply bizarre and would not bring justice to the victims."
A spokeswoman for Prime Minister Theresa May said Britain wants the men to stand trial in the most appropriate jurisdiction.
"We are continuing to engage with the US Government on this issue and our priority is to make sure that these men face criminal prosecution," she said.
What implications could this have?
Kevin Boreham, a former teacher of International Law at the Australian National University, told SBS News Britain’s move weakens global support for the death penalty's abolition.
"If a state like Britain, which has long opposed the death penalty says, ‘well, we oppose the death penalty, except when we don't’ – that’s inconsistent and it weakens the front of opposition to the death penalty. You either oppose it or you don’t. You can’t oppose it to some extent."
Amnesty International found there was almost 1,000 executions in 23 countries in 2017, down 4 per cent from 2016.
The most known executions took place in China, Iran, Saudi Arabia, Iraq and Pakistan, according to the organisation.
Australia opposes the death penalty and is a strong supporter of the United Nations resolution calling for a moratorium on its imposition.
Mr Boreham said the Australian government's reaction to Britain’s move could cause it problems on the international stage.
"If there was a similar situation, which is not impossible, it would then, given the British precedent, would create a difficulty for the Australian government. When you’re dealing with the death penalty against terrorists it becomes a political question as much as a legal question.”