See, this is the sort of binary morality I was talking about. You could plug any bad act into the "plagiarize" slot and your statement would have precisely the same content. The Lehrer who existed three years ago didn't plagiarize all the time, and he probably didn't realize he was plagiarizing at least part of the time he was doing it. He plagiarized in specific situations, and furthermore he probably brought about those situations through his own actions (e.g., exempting himself from fact-checking on a problematic article by concocting an excuse his editor would buy), even if he didn't realize it at the time. Today's Lehrer can endeavor to avoid those situations, and certainly to never bring them about through his own actions, just by being more aware.
I don't say this to excuse Lehrer's actions. All of us humans are the same flawed creatures as he, and we're all judged for our actions. I don't have to believe in the devil, but if I can imagine him, I can imagine a fiend who tempts all humanity, virtuous or not. Then I can make ready for his temptations even though I'm not a bad person like Lehrer.
I'm not here to moralize. In at least some cases, he clearly copied and pasted and then did some minor edits. I don't see how that could have happened accidentally, and therefore I don't think it's unreasonable to ask how having a set of rules is going to help (given that, obviously, it will typically require a certain amount of diligence to follow any set of rules). I'm not saying that it won't help, but if it will, it would certainly be instructive to understand exactly how.
I don't say this to excuse Lehrer's actions. All of us humans are the same flawed creatures as he, and we're all judged for our actions. I don't have to believe in the devil, but if I can imagine him, I can imagine a fiend who tempts all humanity, virtuous or not. Then I can make ready for his temptations even though I'm not a bad person like Lehrer.