British academic Matthew Hedges shook with fear when he was told he was being sentenced to life in prison in the UAE, his wife has said.
Daniela Tejada has been speaking about the five-minute trial and accused the UK government of putting international relations over her husband's right to freedom.
Describing his sentencing in an Abu Dhabii court, she told the Today programme: "He was very, very scared when he was standing in front of the judge, just because we knew the possibilities of there being an arbitrary judgement were there."
She added: "I asked him to look at me if he was feeling too nervous and he tried to do so on a couple of occasions but was asked to face the judge.
"And he started shaking when the translator told him the sentence. He actually had to ask to double-check if he heard right."
Mr Hedges, a Middle Eastern studies specialist, was arrested at Dubai Airport on 5 May and accused of spying in the UAE.
Authorities said his research in the country for his thesis on security policies after the Arab Spring was a "cover" for carrying out surveillance for a "foreign agency", thought to be the UK government.
His family say he has been held in solitary confinement for more than five and a half months, during which his "mental and physical health seriously deteriorated".
Ms Tejada criticised the Foreign Office's handling of the 31-year-old Durham University PhD student's case and said it had failed to take a firm stance with the UAE over his detention from the outset.
She told the BBC: "I was under the impression they were putting their interests with the UAE above a British citizen's rightful freedom and his welfare.
"I believe that they should have taken a firmer stance from the beginning, if not publicly then through their private representations.
"This is something I feel they failed to do throughout, really. They just disregarded my requests, they said it wasn't part of their job, it wasn't part of their duty.
"On one occasion one of the case workers said the Foreign Office did not have a duty of care so weren't obliged to make such representations."
Foreign Secretary Jeremy Hunt is expected to meet Ms Tejada later.
He has warned the UAE of "serious diplomatic consequences" over Mr Hedges' sentence and raised the case with the crown prince during a visit to the country earlier this month.
Mr Hunt told Sky News the UK "will do everything we can to get him home".
"We see absolutely no evidence for any of the charges laid against him. We're very concerned for his welfare," he said.
"The UAE is supposed to be a friend and ally of Britain's. We've given them repeated assurances about Matthew. If we can't resolve this there are going to be serious diplomatic consequences, because this is totally unacceptable."
Ms Tejada's calls for government action were echoed by Tory MP Johnny Mercer.
He wrote on Twitter: "This is ridiculous. Our defence assistance, mentoring and intelligence relationships alone with this country should preclude absurd things like this happening. From a friend and partner, simply unacceptable.
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"Consequences must be immediate until he is released."
A Foreign Office spokesman did not say what form any possible diplomatic consequences could take, but said a number of options are available.