Something that came to mind following a discussion this morning about citing.
Citings happen under IRB Regulation 17. For a citing, the Citing Commissioner has to be satisfied that the offence in question is one for which a player could be sent off - a red card offence (it's Regulation 17.6.2 (a), if you want to check it up; page 3 of the PDF link above).
In quite a few recent citings, the player cited has admitted the offence, but said it didn't merit a red card. In some cases - Jerry Collins' recent one, for example - that's been accepted (by a majority in Collins' case).
The problem is, there doesn't seem to be any definition at all in the Laws as to what is or is not an offence that merits a red card. Law 10 (5), which is the one dealing with sanctions for foul, illegal or dangerous play, is very much along the lines of, "Your call, ref, whatever you're having yourself." The only one at all seems to be the mandatory requirement that anyone committing the same offence for which they have been sin-binned must be sent off in Law 10 (5) (b). And, as anyone who watches the game will agree, that one's ducked all the time.
So, you have a central part of how citing is supposed to work - and it's entirely subjective.
It's a bit like the famous line from the American Supreme Court Justice, Potter Stewart, on obscenity in a case called Nicobellis v. Ohio:
I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description; and perhaps I could never succeed in intelligibly doing so. But I know it when I see it...
If only it were that simple in rugby. Or that precise.