OK, despite of my earlier statements I do not go around slapping everything that annoys me (stupid headwind, *slap*!). But where I ride people do generally know cyclists have rights (the details may be a bit hazy). I have, fortunately, yet to see a cager cut a cyclist off on purpose. They either judge your speed wrong or do not pay attention. I have never heard the "get off the road" -kind of cr@p from passing cars that seems to be so common elsewhere.
I usually agree with "let the cops deal with them", but if the cager did not notice you or understand what went wrong I find it somehow useless. The cop calls maybe 4hrs later, they have a chat and agree to pay more attention to something they have no recollection of. I think it is much more effective to give feedback right away. Even those who failed to see my feeble 85kg body, bright clothes, shiny bike and bright red pannier all heard the slap and reacted to it.
If they cut me off on purpose it would be another matter entirely.
--J