The number of people Canberra's police are arresting has jumped 30 per cent in five years, a possible sign the focus has turned to more serious crimes and restorative justice may be working.
Criminal justice statistics released for the five years to March this year show the number of charges for arrests has rose from 974 in June 2012 to 1331 in the March quarter this year.
That has coincided with an almost 70 per cent fall in cautions issued by police, down from 233 in the June quarter 2012 to 72 in the March quarter 2017.
While an ACT Policing spokesman said such trends could not easily be explained, as arrests and cautions are up to "officer discretion", an Australian National University criminologist said it could be a sign of less youth involvement with the ACT justice system.
ANU senior lecturer in criminology Jason Payne was recently involved in a Criminology Research Council-funded study into declines in crimes in NSW that noted a considerable fall in the number of young people having contact with the police in their early and late teens.
"It seems that police in NSW are simply having fewer interactions with young offenders and this can have a significant impact on aggregate crime statistics," he said.
The ACT Policing spokesman said cautions were largely used for first-time and young offenders, related to less serious crimes, while the criteria for arrests were more often for repeat offenders and serious crimes.
Mr Payne also pointed to the ACT data showing a consistent fall in the number of 15 to 17 years olds in Canberra over the five year period, down from 181 in the June quarter 2012 to 84 in the March quarter this year.
"It is possible that the ACT is following a similar experience, and so cautions are falling because police are simply having to deal with fewer young people in their day to day activities," he said.
Mr Payne also said while the rising numbers of charges for arrests were "trickier to explain", it was highly unlikely the rise was due to police using arrests instead of cautions.
"If that were the case, we'd not have seen a fall in 15-17 year old offenders overall," he said.
"The more likely explanation (one that we suggested was also the case in NSW) is that as the time spent policing minor anti-social behaviour decreases, the time available to investigate and deal with more prolific and serious offenders increases."
He said it also helped to explain more recent rises in "justice procedure" offences, and could be a consequence of rising attention on domestic violence offending.
The police spokesman said it could also be due to a greater focus on "restorative justice", a process involving offenders meeting with victims to discuss the impacts of a crime.
"Where previously police may have cautioned a young offender for the crime, the restorative justice outcome is more beneficial as it provides the victim and offender the opportunity to discuss the incident," he said.