Babar Ahmad, who was among five alleged terrorists who may be extradited to the United States following the ruling, is accused by U.S. authorities of fundraising for terrorists and running a jihadi website.
Ahmad, 37, has been detained pending extradition since 2004, reportedly the longest time a British national has been detained without trial in modern times.
His father Ashfaq Ahmad said the family was disappointed with the ruling and called for his son to be allowed to go on trial in Britain immediately.
“Babar is a British citizen accused of a crime said to have been committed in the U.K., and all the evidence against him was gathered in this country,” he said at a press conference at his home in south London.
“Nevertheless, British justice appears to have been subcontracted to the U.S. This should be immediately rectified by putting Babar on trial in the U.K. and ordering a full public inquiry.”
Fahad Ansari, a lawyer and Babar Ahmad’s brother-in-law, said the family planned to make use of a three-month appeal period granted by the European court.
The defendants claim that conditions at the ADX supermax prison in Florence, Colorado, and possible multiple life sentences they face would be grossly disproportionate and amount to inhumane or degrading treatment.
Ansari said he feared his brother-in-law would suffer “psychiatric problems” if he was detained at ADX.
“Babar has already spent eight years in detention without trial in this country, is facing up to three years pre-trial in solitary confinement, after which he would face up to a life without parole in those conditions,” he said.
“It is completely inhumane.”
In an interview with BBC television last week, Ahmad admitted that he had fought “battles” in Bosnia but said he believed “terrorism to be wrong”.
He was first arrested in 2003 in a major counter-terrorism operation by London’s Metropolitan Police, but released without charge.
The force later paid him £60,000 ($96,000, 73,000 euros) in compensation after he was severely assaulted during the arrest.