The trial of euthanasia campaigner Sean Davison began at the High Court at Dunedin this morning.
The 49-year-old is accused of the attempted murder of his mother Dr Patricia Elizabeth Ferguson in Dunedin in 2006.
Dr Ferguson, 85, was terminally ill.
Davison has said he gave her a dose of morphine the night she died.
The father of two, who since his mother's death has become a campaigner for legalised euthanasia, has pleaded not guilty to attempting to murder her.