The policeman, Ahmet Sahbaz, is accused of killing a 26-year-old anti-government demonstrator, Ethem Sarisuluk, in June.
He was never arrested but was charged with committing manslaughter while on duty.
The victim's family had asked that he be kept in custody for the duration of the trial but judges decided his testimony would be taken via video conference, said Turkey's Anadolu agency.
Police on Monday dispersed a crowd of some 2000 demonstrators with water cannon and tear gas after protests erupted over the court's decision, according to Anadolu Sarisuluk was fatally wounded in the early stages of anti-government protests that swept Turkey in June.
His family says he was killed by a bullet fired by Turkish law enforcement.
Sarisuluk was in a vegetative state for nearly two weeks before he died.
Anadolu Agency reported that the policeman's lawyer claimed at the hearing on Monday that his client acted in self-defense.
Anti-government protests broke out in late May after police cracked down on a sit-in to protect an Istanbul park.
That sparked nationwide protests against the government's increasingly authoritarian style.
Monday's hearing was the second in a case that started to be tried in September.
On Monday, the next hearing was postponed to December.
NJF/NJF