There have been 100 internal investigations by the police into the use of excessive force on young people since 2015.
Of those, 21 were upheld, two resulted in charges and one in a conviction for common assault, according to police figures obtained by First Up.
The investigations included the use of a firearm that wasn't discharged, the use of batons, tasers, pepper spray, dog bites and restraints among others.
Fourteen investigations, dating back to 2018, were ongoing.
Tania Sawicki-Mead from youth justice organisation Just Speak said the figures were incredibly worrying.
"Those kind of interactions set up how people view police in their community and shape people's perceptions of police throughout the rest of their lives," she said.
"It's not just a question of what is appropriate for children ... it's also about how does this shape people's understanding of, trust of, and relationship with police."
Sawicki-Mead said the use of police dogs was particularly disturbing, and would likely have a serious impact on how a young person viewed the youth justice system.
She said it could potentially undo any further work by the system to divert a young offender away from crime, which is what the youth system is designed to do.
"If the front line police officer is the child or young persons' first experience or first contact with the justice system, to go on to be referred to a specialist youth response team, it's almost possibly too late to be dealt with in a specialist way."
AUT law lecturer Khylee Quince. Photo / File
AUT law lecturer Khylee Quince said police did have youth aid officers who were specially trained to deal with young offenders.
But they weren't always the first on the scene, which was why Quince said regular officers should also receive youth-specific training.
In a statement, police national youth manager, Darrell Harpur, said police were focused on supporting young people to avoid the criminal justice system.
He said that included fostering partnerships with iwi and increasing youth-specific training.
"Last year, changes to the Oranga Tamariki Act mean that most 17-year-olds are now included in the youth justice system, rather than the adult courts," he said.
Tania Sawicki-Mead. Photo / File
"Following this, police around the country received youth justice training, which touched on what we already know - that the actions of young people can often be more impulsive that fully-grown adults, as their decision-making skills take time to form."
