You have to make the consequences of non-compliance greater than the coverup.

Make a lien on the pension which forces the old guard to feel uncomfortable and request department changes.

Make this occur for the slightest infractions of any individual officer.

Make the municipality have to disclose very significant policing stats when they want to issue a bond, and then quarterly. They currently have a complete disclosure exemption from the SEC.

Turn on these consequences every time a police report doesn't match the video. Or whenever one just lies whether there is video or not.

Make the partners accomplices when they don't report, and that alone being a trigger for the wide range of sanctions against the entire municipality.

There are a lot of ways to make them turn on themselves, while keeping their primarily stated concern of being able to make split second decisions and get home safely at the end of the day.

This would be much better than requiring all this fanfare for a small subset of egregious transgressions.