Joe Hollander, JP, president of the Royal Federation of Justices for the Central Districts, told Mrs Kerr the tasks she had made herself available for were many and varied.
"You've received your initial training in preparation for your duties.
"This is a long and honourable tradition and you will benefit from ongoing education and training and being part of a team," he said.
"It's clear you already serve your local community in many ways and will continue to do so."
Mrs Kerr's family and colleagues from the Tararua District Council were in court to see her sworn in.