The Sensible Sentencing Trust has launched a new website that grades the performance of judges and calls for their sentencing notes to be made public in written form.
But the Law Society says judges' rulings are already freely available in court and it would be an administrative burden to require all rulings to be typed up.
Trust spokesperson Ruth Money says the website is part of a campaign to get all judges' sentencing notes released as a matter of course.
She said that would allow decisions to be widely discussed and give victims of crime a better understanding of how the sentence was arrived at.
But the convenor of the Law Society's Criminal law Committee says every sentencing is publicly available to anyone who wishes to attend court and listen.
Jonathan Krebs said it would be an onerous task to transcribe the huge number of sentences for crimes such as drink-driving and burglary.
The Ministry of Justice's district court general manager said New Zealand already has a very open court system.
Tony Fisher said judges' sentencing notes can be widely accessed by the general public on application to the Registrar of the Court.
Playing cards used to rate judges
The Judge the Judges website publishes decisions and grades the performance of judges using playing cards.
Judges whose sentences the trust disapproves of are given a joker, while judges it approves of are given an ace of hearts. Nine of the 12 judges featured have been given a joker.
Ruth Money said the site has had about 8000 page views since it launched on Monday morning and there has been positive feedback, including from victims of crime.
Ms Money said the site is intended to be a measured, accurate and informative resource to record judicial decisions and encourage debate.
The site would be updated regularly with new and historical cases, she said.