How many news stories about assorted situations have we read where exactly this happened - someone was arrested and then released (sometimes the next morning with no charges, or all charges dropped? At that point, you get to pay $400/hr (less the hyperbole) to try to prove that the officer had no probable cause to arrest.
As for whether complaints matter - how many cases - like Chauvin, like Pantaleo (who was the one choking Eric Garner) - have had previous complaints and kept their job?
Pantaleo and a partner won a civil lawsuit previously brought because of their actions:
Pantaleo was the subject of two civil rights lawsuits in 2013 where plaintiffs accused him of falsely arresting them and abusing them. In one of the cases, he and other officers allegedly ordered two black men to strip naked on the street for a search and the charges against the men were dismissed.
Gives a whole new meaning to “strip search”. But note again, charges against the arrested men dismissed. Officer still on force until 2019. Did not even get indicted for a death due to “compression of the neck”. The death happened 2014, there were (by Wikipedia) 3 disciplinary hearings in 2019. and the officer was only fired when the media found out a judge had said he should be.
My point here is not to debate the death or the punishment, but to point out that this is what happens, even in something as serious as a death. Hired experts actually said Garner was not choked (and others said he was), did not die from choking, would have died anyway. Between the thin blue line and normal authoritarian desire to hide any mistakes - if all that happens to you is you are held in jail overnight and let go, unless it is a national media firestorm, nothing will happen to the officer.
I see the point - qualified immunity - that police should not have to spend a week in court being sued over every little judgement call they make; but sometimes some will overuse that level of immunity.
OTOH, I suppose the simplest advice is best. Whether it’s a speeding ticket or mass murder, if the police have decided to do something like a ticket or arrest, you’re not going to talk your way out of it. They’ve heard every excuse in the book. What you can do, is talk your way deeper into it.