Between 2015 and 2017, 67 guilty pleas were entered, compared to 18 denials. Diversion and discharges without conviction had been granted in some cases. The figures show most convictions, 12, were registered in Christchurch, followed by six in Auckland and five in Nelson. The rest were spread across the country's district courts.
Retired judge and University of Auckland law academic David Harvey has been researching the figures since the law was enacted, and said the number of subsequent prosecutions was more than anticipated.
Although the legislation intended to target cyber bullies or internet 'trolls', his research unexpectedly showed most prosecutions involved broken relationships, he said.
The majority of the offences were committed by ex-partners or partners who threatened to publish intimate photos or videos, sent threatening or obscene images or texts, or disclosed the victim's personal details, he said.
"Looking at analysis for motive of offence, it can be seen that a majority of the offences in this data set were committed out of anger/frustration of break-ups and marital breakdowns," he said.
"In most of the cases there has been some connection between offender and victim.
"Although the prosecutions could arguably be characterised as cyberbullying it lacks many of the aspects of the persistence that accompanies traditional cyberbullying or internet trolling," he said.
"So I don't think that the law was overdue for enactment but I think that what has happened is that the law of unintended consequences has come into focus and a wider cohort of offenders has come within its scope than was anticipated."
One of the first offenders prosecuted was a Dunedin teenager who threatened to send nude photos of his ex-girlfriend to her parents.
In a separate case, this month Tyla Britten, 21, appealed his jail term to the High Court, after posting naked photos of his ex-girlfriend online along with her identity and contact details.
His 12-month jail term was reduced to seven months.
Another case that reached the High Court was the conviction appeal of a man who used Facebook to contact his ex-spouse, who had a protection order against him. He subsequently posted pictures of her online.
His conviction was upheld.
Netsafe, the agency tasked with receiving and investigating complaints, said since the law was enacted the agency had fielded a rising number of complaints every quarter.
Chief executive Martin Cocker agreed the number of convictions was higher than expected, and that the agency had seen a growth in the number of revenge porn cases.
It was "too early" to say if the act was making a difference in its deterrence and awareness of the harmfulness of cyberbullying, he said.
THE FIGURES
2015- 2016: 14 guilty pleas, two not guilty pleas
2016-2017: 53 guilty pleas, 16 not guilty pleas
CONVICTIONS
Christchurch District Court: 12
Auckland courts: 6
Nelson District court: 6
Invercargill District Court: 3
