The police say officers reporting on their colleagues is one reason more staff are being charged with serious offences.
Figures released under the Official Information Act show 14 officers went through the courts last year, compared to just six and five in the two years before that.
Police general manager of human resources, Wayne Annan, says one reason for last year's marked increase in assault charges is more internal reporting.
"Police officers (are) informing us of things they are uncomfortable with."
Mr Annan says the spike in violence charges can also be put down to an increase in staff numbers and New Zealand becoming a more violent place.
Most common charge is assault
The figures show overall 66 officers were charged with crimes between 2007 and 2009.
Two were accused of rape, 14 of excess breath alcohol but the biggest number, 25, was for assault. There were also dishonesty charges, for theft and fraud.
Mr Annan could not say how many officers were acquitted, but he two were sacked and 20 either resigned or retired before they could be dismissed.
Of the 125 officers to face serious internal disciplinary proceedings during the same timeframe, one was dismissed and 68 either retired or resigned.
Police were unable to say how many officers are still receiving retirement benefits. Some cases are still before the courts.
Police Association president Greg O'Connor, says while the figures are not a good look, they show an organisation that's open about the action it takes against its staff.
He says if an officer is charged, the police become the prosecutors as well as the employers and so they're more likely to let the courts decide the outcome.
He says the police are much harder on their own, than on members of the public.
