It's a rule of thumb that roughly 10% of the NYPD receive 99% of the complaints and claims of excessive force. 90% of the NYPD is fine. The issue is that there is no meaningful oversight mechanism to correct the 9% that behave inappropriately sometimes, or the 1% that are serial offenders and are dangerous to the public. Other cops stay silent about it because there's nothing more dangerous to health and career than being a cop that rats out other cops. The civilian oversight board can't even look at records without the permission of the police.

Brief article about police complaints data:

https://www.theguardian.com/us-news/datablog/2020/aug/04/new...

Example of the ineffective oversight:

https://www.propublica.org/article/my-family-saw-a-police-ca...