Customer service survey after every dealing with the police
Some time ago I ranted how I hate being invited to fill out a customer service survey after every bloody transaction in the online world. Companies don't seem to clue in that if they ask for surveys too much, they end up getting the opinions only of the angered or overeager.
But there's one place this might make sense. I think you should get a chance to do a survey after every interaction with the police, as well as others who have some color of authority over you (judges, security guards, border patrol etc.) The data you enter would be anonymous, and the survey conducted by a different party bonded to protect your privacy. There would also be entry in some means (perhaps with different classes of card) about whether the encounter was assistive, or was a stop, or lead to arrest though there are limits on this while keeping the data anonymous. If you are required to identify yourself as part of the encounter, this can be your means to getting a card later, though again the data entered must not be tied to your name.
Police would get small cards which have a cryptographic code which allows the bearer to fill out the survey. They would be required to hand one out in any incident. The number handed out would need to be close to the count in their own incident report, so that they don't just keep the cards to fill out positive surveys on themselves. If police won't give you a card that's a serious matter itself.
Of course, people who have been stopped, rather than assisted by police will have a naturally antagonistic view. What would matter in these surveys would be how each officer compares to the other officers. You would not judge officers on their absolute score, but their score relative to other officers with similar duties. These scores would be admissible in court when an officer testifies. An officer with a seriously bad record would become less trusted by judges and juries. The worst cops would have to leave the force, being unable to testify in court without being doubted. And the absolute numbers would also tell us something. On the forms, people could complain about misuse of authority and corruption, and could also leave positive remarks.
The 3rd party taking in the data would have to have impeccable credentials so people trust that it truly destroys any association between submitter and data. They would also have to be trained at how to protect against re-linking. (For example, if dates can be figured out, officers may well be able to connect people with forms. As such data must be released slowly, and only after a large enough number of forms are in the batch, and forms with unique profiles must be merged with care.) In most cases the 3rd party would have to be in another state, and possibly another country to assure it is not under the sway of those it is collecting data on.
We also would have to assure that people don't try to sell the survey cards. That's hard, if they are to be truly anonymous. You might have to use them quickly, to avoid giving you time to find a buyer. The 3rd party could run regular stings trying to buy and sell cards and pierce anonymity on just those. I'm sure that there are other ways officers would try to game the system that would have to be found and dealt with. Over time, the data should become public in amalgamated form, not just available to defence lawyers.