The claim at the High Court is expected to last seven days
A terror suspect awaiting extradition to the US is suing the police after claiming he was the victim of assault.
Babar Ahmad says he was punched repeatedly and choked to the point of unconsciousness when he was arrested at home in Tooting, south London, in 2003.
The 34-year-old is taking his civil claim against the Metropolitan Police to the High Court in London.
Mr Ahmad is accused of raising money to support terrorism in Chechnya and Afghanistan via websites and e-mails.
He was arrested at dawn by anti-terrorism officers from the Territorial Support Group on 2 December, 2003.
His lawyers will argue in the claim launched on Monday that he was punched repeatedly during the police operation, and was forced into a kneeling Muslim prayer position and asked: "Where is your God now?"
It is also claimed one officer used a dangerous neck-hold, bringing Mr Ahmad close to passing out.
Photographs show injuries he sustained, although the Met claims they were largely self-inflicted.
Parts of the case will be held behind closed doors for legal reasons.
An Independent Police Complaints Commission (IPCC) investigation in 2007 led to no action being taken against any officer.
The IPCC concluded Mr Ahmad's claims were "unsubstantiated" and cleared the police of any wrongdoing.
His family said in a statement: "We hope that after almost six years of campaigning, complaints and litigation, the truth will finally emerge of what happened to Babar on 2 December, 2003."
The case is expected to last seven days.
US investigators claim he was behind the website azzam.com which was one of the most well-known terrorist fundraising sites on the internet at one point.