The defendant is a 27-year-old ethnic Armenian resident of Tbilisi. Vladimir Arutyunian was arrested in July following a shoot-out that left one Georgian policeman dead.
Georgian authorities have released police videos showing Arutyunian purportedly confessing to throwing the grenade with a view to harming Bush. But Arutyunian has so far refused to testify at his trial, saying he would do so only in the presence of Western human rights campaigners.
The defendant faces life imprisonment.