District, Family and Youth courts have started using te reo Maori as well as English as a permanent new part of the court process.
Chief District Court Judge Jan-Marie Doogue presided over the first session at the Auckland District Court on Monday morning.
District Courts regional manager Nichola McKinney says it was historic day for New Zealand courts.
Ms McKinney says from now on all opening and closing announcements will be made in te reo.
Monday also marked the beginning of Maori Language Week 2012.
On 1 August, it will be 25 years since the campaign for more use of te reo began.