Alleged computer hacker Lauri Love is to find out if he has successfully challenged a ruling that he can be extradited to the US.
Two judges sitting at the High Court in London will give their decision on Mr Love's appeal on Monday.
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, including the "high risk" that Mr Love, who suffers from Asperger syndrome, would kill himself.
Authorities in America have been fighting for Mr Love to face trial on charges of cyber-hacking, which lawyers have said could mean a sentence of up to 99 years in prison if he is found guilty.
Mr Love, 32, who lives with his parents near Newmarket in Suffolk, and also suffers from a depressive illness and severe eczema, is alleged to have stolen huge amounts of data from US agencies, including the Federal Reserve, the US army, the defence department, Nasa and the FBI in a spate of online attacks in 2012 and 2013.
In September 2016 a district judge at Westminster Magistrates' Court ruled that Mr Love could be extradited. The High Court appeal centred on that ruling made by District Judge Nina Tempia.
Edward Fitzgerald QC, for Mr Love, submitted there were "overwhelming reasons of justice and humanity" why any trial should take place in the UK.
He argued it would be "unjust and oppressive" to extradite him because of his severe mental disorders.
Peter Caldwell, representing the US, made submissions inviting the judges to dismiss Mr Love's appeal.
In written argument he said the district judge's conclusion on extradition was "reasonably open to her on the findings of fact she made".
Having identified a high risk of suicide, she "properly assessed whether and how that risk could be managed were the appellant to be extradited".