Violence, sexual misconduct and drink-driving are among more than 1000 allegations against police staff under internal investigation.
Figures released under the Official Information Act show 152 officers are alleged to have used "manual" force while on duty, making up 15% of all professional standards inquiries nationally.
Failed investigations were the second-largest complaint (74) with 20 of those in the Wellington district alone, followed by 58 complaints of unacceptable behaviour or language nationally.
Twenty-six pursuits of fleeing drivers - in which someone was killed or injured - are under scrutiny, while just one complaint of baton force is recorded, two of Taser shock, three of OC (pepper) spray and 11 of dog-bite injury.
There are 16 allegations of sexual misconduct (12 in the workplace), 28 of disgraceful behaviour (12 while off-duty), seven of drug or alcohol abuse and nine of drink-driving.
Alleged breaches of official police conduct include dishonesty (33), corruption (21) and conflict of interest (4).
While there are 1029 active professional standards investigations, on average, 275 complaints are upheld each year, or 8% of all complaints.
Of those, criminal charges have been laid against 37 staff in the past five years. Just eight have been sacked and 46 have resigned over that period.
Charlie Busby, acting national manager for conduct, said the police - who have about 8500 sworn staff and 3000 civilian employees - were also closely watched by the auditor-general, the Independent Police Conduct Authority and Dame Margaret Bazley's commission of inquiry.
Greg O'Connor, the president of the police union, said staff should live under close scrutiny and the public should demand that police were professional and did not act with brutality or behave corruptly.
But he was concerned when officers were investigated for "vexatious" allegations that arose from simply performing their duty, and he warned of the dangers of creating a "tentative" police force.
"No-one, least of all police officers, want people in the police who shouldn't be here," said Mr O'Connor.
"But because police are constantly accused of looking after our own, which is a myth, we've gone the other way for fear of being criticised.
"It's about maintaining a balance, because these complaints take up a huge amount of time and resources. I mean, an officer can be investigated for swearing, or if someone doesn't like their attitude."
Auckland barrister Richard Earwaker has defended police officers on criminal charges for 15 years, with all but two acquitted.
He said the police organisation was susceptible to criticism and therefore more likely to "err on the side" of charging officers when complaints of assault were made - when they should not.
"Police are authorised to use force in the course of their job, because they're dealing with difficult people. There are times when you have to use force and it's a judgement call, which is difficult in the heat of the moment.
"You can't worry whether or not you'll face a disciplinary complaint or criminal charge. You can't have police being scared to do their jobs, because that's when people get killed or hurt."
Auckland barrister Todd Simmonds also represents police officers, most recently the two AOS officers who accidentally killed 17-year-old Halatau Naitoko in the pursuit of a gunman.
He said police these days were far more accountable for their actions but he believed there were some cases where criminal charges were wrongly laid against police officers.
Even after being acquitted in court, officers could still face internal disciplinary action ranging from a warning to dismissal.
"For those that are ultimately cleared of wrongdoing, they often feel betrayed and let down by their own organisation for, effectively, putting them through the ringer," Mr Simmonds said.
