The only man found guilty over the 11 September terrorist attacks in the United States has had his conviction overturned on appeal.
Moroccan student Mounir El Motassadeq had been jailed for the maximum 15 years by a court in Hamburg in Germany, for being an accessory to the murder of more than 3,000 people.
Germany's Supreme Court effectively accepted a complaint by the student's lawyers that his defence had been unfairly hindered by the refusal of US authorities to allow testimony from a key witness.
There will now be a retrial.
