Lawyers for a jailed former senior Northern Ireland civil servant believe his continued imprisonment in America is doing him irreparable medical and psychiatric harm.
Stan Mallon was due to be released from prison after serving a sentence for a sex offence on Wednesday, but that has been delayed.
Mallon was jailed for 21 months in March, after admitting using an internet chatroom to contact a girl who turned out to be an undercover FBI agent while on a stopover in Chicago on his way to a White House reception.
The former acting chief executive of the Ulster Scots Agency escaped the maximum sentence of more than four years in prison after the judge ruled that he was suffering a “diminished capacity”.
His sentence is being contested by prosecutors who believed it was too lenient and will argue at an appeal that it should be doubled.
They have argued that Mallon was a “highly-functioning individual” when he set up a liaison with a girl he believed was 14.
The court ruled on Tuesday that Mallon should stay in jail until that appeal is heard.
Mallon, a father of five from Crumlin, County Antrim, who is in his 60s, was due to be released on Wednesday and deported on Friday.
However, that has been blocked pending an appeal court hearing which is scheduled for Thursday.
However, a judgment will not be delivered until later in the year.
Mallon’s American lawyers say his continued incarceration – when he has completed his sentence – magnifies and continues his hardship.
It has also emerged that when he does return home he will not automatically be placed on the sex offenders register as the offence happened outside the UK jurisdiction.