Abdelkader Ghedir was arrested in November 2004 by police who belived he was one of a group of youths who had thrown pebbles at a train in a Paris regional station.
Fourteen years later he is confined to a wheelchair and judged to be 95 percent disabled, unable to carry out everyday tasks without help.
The railway security officers who first detained him handed him over to national police and the two groups' accounts of the arrest vary.
While the railway police said it was a "model" procedure, the national police said it had been "robust", some saying they saw one of their rail colleagues knee Ghedir in the face while he was pinned to the ground.
Another witness says he was hit with a truncheon while being handed over, according to France Info radio.
In coma for three months
After being taken to a police station he lost consciousness, falling into a coma that was to last three months.
Today, at the age of 35, he is still suffering the long-term effects of the treatment he received, according to the court's ruling.
Ghedir's case against the police was dismissed by a French court in 2010, after it concluded that he had been abusive and violent at the time of his arrest and that the security officer accused of kneeing him had used a restraint technique.
Two appeal courts also rejected the case, leading his lawyers to take it to the European court.
After a hearing in 2015 found Ghedir had suffered inhuman or degrading treatment, the court this year awarded 6,500,000 euros in compensation and 39,950 costs in a ruling that took effect earlier this month.
It also found the suspicion that led to his arrest was unfounded.