US President Donald Trump could intervene in the case of an American man arrested in Co Antrim over a drugs-related murder in Florida, the High Court heard today.
Jonah Horne, 24, is being sought in connection with the fatal shooting of Jacob Walsh three years ago.
In March a judge in Belfast ruled that he should be discharged from custody.
American authorities are now appealing that decision in a further attempt to secure the extradition of Mr Horne over his alleged role in the murder.
He is fighting the legal bid amid fears that he could spend the rest of his life in jail if convicted.
But counsel representing the United States, Tony McGleenan QC, stressed that prosecutors have given assurances they would seek no more than a 40-year sentence.
Similar pledges about cooperating on mitigation in those circumstances have been endorsed at a federal level, the court was told.
One of the judges hearing the appeal, Sir Donnell Deeny, questioned what would happen if Horne's extradition was ordered and those assurances were ignored following any subsequent conviction.
Referring to the options for substituting a lesser sentence, he asked: "Would this be an instance where presidential commutation might be a live possibility?
"At that level of government they would be conscious of not upsetting the long-standing extradition (arrangements) between the United States and the United Kingdom."
Mr McGleenan replied: "I wouldn't put it any higher than a possibility, but it is a possibility."
Mr Walsh, 25, was shot outside apartments at North Military Trail, Boca Raton on June 7, 2016.
His killing was associated with an apparent drug deal, according to reports at the time.
A previous court heard claims that Horne's DNA, video and witness evidence links him to the murder, with the victim's blood said to have been found on a vehicle connected to the wanted man.
He was detained under a provisional warrant at a house on Drumard Drive, Lisburn in March 2017.
Since then, however, he has contested attempts to have him returned to the US.
Horne's lawyers denied that he is a fugitive who fled following the fatal shooting.
Instead, they contended, he fell in love with a woman from Northern Ireland and travelled to be with her.
Central to his case is uncertainty surrounding any guarantees over the maximum period he would serve behind bars if ultimately found guilty.
Counsel for Horne, David McDowell QC, argued: "There's a real risk of an irreducible life sentence, and no assurance has been given yet to mitigate it."
Reserving judgment after hearing the appeal with Sir Donnell, Madam Justice McBride said: "This is a difficult and important matter we will have to determine."
Horne was remanded back into custody until the ruling is delivered at a later date.