The Westboro Baptist Church believes the war in Iraq is a punishment for the tolerance of homosexuality in the US.
Albert Snyder sued after members demonstrated at the funeral of his son, Marine Lance Corporal Matthew Snyder, who was killed in an accident in Iraq last year.
Church members waved signs reading “Thank God for dead soldiers” and “Fag troops”, even though the young man was not gay.
The federal jury awarded $2.9m in compensatory damages, $6m in punitive damages for invasion of privacy and $2m for causing emotional distress.
But one of the church’s leaders, Shirley Phelps-Roper, said the members would continue to picket military funerals.
Church members routinely protest at funerals of military personnel killed in Iraq and Afghanistan, carrying signs such as “Thank God for dead soldiers” and “God hates fags”.
But the Snyder case is believed to be the first by the family of a dead serviceman. The church and three of its leaders — Fred Phelps and his two daughters, Phelps-Roper and Rebekah Phelps-Davis — were found liable for invasion of privacy and intent to inflict emotional distress.
It was unclear if Mr Snyder will be able to collect the damages, given the church's lack of assets.