An alleged computer hacker will find out later if he has successfully challenged a ruling that he can be extradited to the US.
Lauri Love, 32, from Stradishall (nr Newmarket), Suffolk, is suspected of hacking into FBI, US Central Bank and Nasa systems.
Speaking on the BBC's Today programme earlier his father said his son was "very distressed" and "afraid".
Two judges sitting at the High Court in London are expected to give their decision on Mr Love's appeal later.
Lord Chief Justice Lord Burnett and Mr Justice Ouseley heard argument on his behalf during a hearing in November that extradition would not be in the "interests of justice" for a number of reasons.
These included the "high risk" that Mr Love, who suffers [sic] from Asperger syndrome, would kill himself.
Lauri Love: Hacking suspect awaits extradition appeal decision