He was convicted and sentenced to five months' home detention, to be served at a friend's Kaikorai address.
Two months into his sentence, Davison remained unrepentant in Dunedin yesterday.
"I acknowledge that assisting my mother's suicide was illegal. Yes, I broke the law. But, I believe I was not judged for what I did; I was judged for writing a book and telling the truth.
"My sole reason for being there was to keep her alive and make her as comfortable as possible. She kept saying: 'Help me to die.' She just wore me down. I believe any humane person would have done what I did if faced with the same circumstances.
"She was a doctor and she was desperate to die. She went on a hunger strike, because she thought it would work. If I committed a crime, it was a crime of compassion to help my mother."
Davison said it was "a huge shock" when he was arrested, but that he bore no malice towards the police for pursuing the investigation, or the judge for convicting him.
"It is their job to uphold the rule of law and I respect that ... I was always mentally prepared for the outcome. I know that when morality and the law collide, morality will always come out worse.
"But, I believe the present law has been exposed in my trial and it stands guilty in the name of justice and humanity. There are many people who have had similar experiences to the one I had.
"The only difference between my experience and theirs is that I wrote a book about mine. It is time that the law was changed to stop making criminals out of non-criminals."
Davison's partner, Raine, and children, Flynn, 3, and Finnian, 1, have been waiting for his return to Cape Town since he was sentenced in the High Court at Dunedin on October 27 last year.
Davison said it had been a terrible toll on his family back home.
"Hopefully, my unfortunate situation can help bring about some good. If there is no law change, people will continue to have dreadful, undignified deaths similar to my mother's and family members who assist in the death of a loved one will continue to face significant legal consequences," he said.
"I've got a platform now, as a result of the trial, and it would be cowardly to walk away."
He will complete his home detention sentence on April 25.
Dunedin voluntary euthanasia support group Exit International convener Paula Westoby said Davison had made "a brave stand against a terrible law".
- Otago Daily Times