It's a forum thread, or maybe it's a blog post, or some other comment.
You have discussions going back and forth, and usually your members are sensible, they upvote what's useful, that gets highlighted at the top of the whole thread. All is well.
Sometimes, though, the conversation doesn't really have anything worth highlighting, and so your members don't upvote anything.
Except that one person, who feels their comment is the most important, and so upvotes their own, so that it's highlighted at the top of the thread, forcing you to monitor and go in and downvote it so that it's demoted.
But that also leaves an audit trail, invites discussion and disgreement, "why did you downvote me?".
I would rather silently remove up or downvotes, but more importantly, prevent someone from upvoting themselves.
How can this be governed?