Susan Austen's lawyer took just 40 minutes, and a statement from one witness, to present his client's defence in the High Court at Wellington.
Dr Donald Stevens, QC, had the registrar read the statement of clinical psychologist Professor Glynn Owens to the court on Wednesday.
Austen, 67, a Lower Hutt teacher, is accused of assisting Annemarie Treadwell to take her own life in 2016, along with two other counts of importing Class C controlled drug pentobarbital, on two occasions between 2012 and 2016.
Owens has spent more than 30 years studying, lecturing and writing about the psychology of death and dying, particularly looking at euthanasia.
His evidence, read out by the court registrar, said that merely possessing "end of life" drugs, such as pentobarbital, can actually ease suffering.