Dr Bruce said the way 16-year-olds were treated through the Youth Justice System compared to 17-year-olds was "very, very different". She said serious offenders 16 and under usually had a family group conference.
"That is a really, really serious thing for a young person to be involved in. They have to face the person who has been victimised, they have to be held accountable for their behaviour."
Justice Minister Amy Adams said including 17-year-olds in the youth court process was being investigated to see if it would effectively reduce re-offending.
"The bottom line for me is what is going to give the best results not only for the 17-year-old cohort but for their current and future victims. "In the end it's a decision for Cabinet, and we'll make announcements in due course."
Youth advocate for Sensible Sentencing Trust Jess McVicar created a counter-petition, which asked Parliament not to raise the age of the youth justice system.
In a press release, Ms McVicar said it would be a "terrifying thought" for victims and the public if the age was increased.
"If the age is increased to 21 it means that offenders under that age will not have a criminal record, their names and crimes committed will not be known to the public, putting our communities at risk and the offenders will be able to roam and offend with complete anonymity."
As at 3.30pm yesterday, 3670 people had signed JustSpeak's petition which was created about a month ago, and 466 had signed the petition created by Ms McVicar about three weeks ago.
- From 2008 to 2016, the number of young people aged 14 to 16 charged in court declined by 62 per cent, from 4983 to 1899.
- The number of 17- to 19-year-olds convicted in court decreased by 63 per cent between 2008/09 and 2015/16, from 19,351 to 7185.
- Ministry of Justice