The pathway to hell is paved with good intentions. No good deed goes unpunished.
There is no shortage of truisms to suggest that you're better off not tempering justice with mercy and being a merciless hardass 24/7. But the fact remains, most people appreciate the occasional verbal warning. Certain, quite a few of us extend the occasional amnesty to one another under the umbrella of "professional courtesy." And most of the time, it doesn't come back to bite us in the hind quarters. Indeed, most citizens are genuinely surprised and appreciative to find out that we weren't quite the jackbooted thugs that they'd anticipated we might be.
But then there are those who, whether or not they've been given a break, are hell-bent on trying to extract their pound of flesh for some perceived slight. Often, it has to do with the fact that we had the temerity to detain them in the first place. No matter how justified the detention, no matter how strong the probable cause, no matter how polite we may have been, they just aren't satisfied.
We've all received the summons, "You're needed in the watch commander's office." In the moment we hear those words, we already know what it's about: some son of a bitch called and beefed me.
Fortunately, rarely do their complaints come as total surprises. It was probably communicated in the shit-eating grin they flashed at you as they stalked back to their car or peddled away on their bicycle. Something in their manner that said, "OK, if you want to play that game..."
Well, if we're going to play the game, then we'd better be keyed into the signals like any good coach. More importantly, we'd better act on them. What this boils down to is if you anticipate that someone is going to complain about you, give them something to complain about.
I don't mean to justify their complaint, but to document the transgression that put them on your radar in the first place. If you pulled him over for a traffic violation, scratch a docket. If they were high on meth, take their ass to jail. In those circs where you don't have enough for an arrest, make sure you have enough for a detailed log entry explaining the basis for your detention.
As a supervisor, I was unpleasantly surprised by how many guys wouldn't do something to mitigate the likelihood of getting a complaint, or at least cover their ass in making sure that the complaint would not be founded.
Protect yourself. If you don't already have a concealable digital recorder, get one. If you have one, use it (stock up on those AAA batteries). If the situation seems to be getting off to a rough start, treat any citizens in the area as an actor playing a protagonist in a drama would (which shouldn't be much of a stretch for even the least thespian-inclined as it pretty much boils down to what you're doing anyway). Develop their sympathies and be as patient as possible.
Having a field supervisor respond to the scene can help. For one, they can do conflict resolution. For another, if the supervisor fails to mollify them, then he might succeed in pissing off the complainant even more so that you look positively angelic by comparison. That's why they get paid the big bucks.
In any event, you want someone to run some interference for you before it gets to the watch commander's attention. Many agencies have adopted such asinine anal retentive measures that effectively remove all discretion from the hands of the acting station commander. This is what finds beefs from wackos who allege that some cop stole their ovaries being more than just an interesting anecdote from Joseph Wambaugh's Hollywood Station, but a true life adventure of fictive paranoia.
Kahlil Gibran said that most hover dubiously between mute rebellion and prattling submission. It's sad to think that in our world, they might be the good ones.