Its not what they MUST do, its what they are ALLOWED to do and NOT ALLOWED to do that is relevant.
Much of Law 16 and Law 17 are repeated word for word with "maul" substituted for "ruck". Other offences not specific to mauling/rucking, joining and offside are covered in, appropriately, "Other Offences"...
[LAWS]17.3 OTHER MAUL OFFENCES
(a) A player must not try to drag an opponent out of a maul.
Sanction: Penalty kick
(b) A player must not take any action to make the opposing team think that the ball is out of
the maul while it is still in the maul.
Sanction: Free Kick
[/LAWS]
[LAWS]16.4 OTHER RUCK OFFENCES
(a) Players must not return the ball into a ruck.
Sanction: Free Kick
(b) Players must not handle the ball in a ruck except after a tackle if they are on their feet and
have their hands on the ball before the ruck is formed.
Sanction: Penalty kick
(c) Players must not pick up the ball in a ruck with their legs.
Sanction: Penalty kick
(d) Players on the ground in or near the ruck must try to move away from the ball. These
players must not interfere with the ball in the ruck or as it comes out of the ruck.
Sanction: Penalty kick
(e) A player must not fall on or over the ball as it is coming out of a ruck.
Sanction: Penalty kick
(f) A player must not take any action to make the opposing team think that the ball is out of
the ruck while it is still in the ruck.
Sanction: Free Kick[/LAWS]
Please note that there is NO equivalent of Law 17.3 (a) in the Ruck Laws. Dragging a player out of a Maul is specifically outlawed in Law 17, but Law 16 is completely silent on dragging a player out of a ruck. If you PK a layer for doing so, then you are making it up as you go.
Dragging a player out of a ruck is in fact a coached technique in this country (I coach it myself for our juniors). I have seen it done hundreds of times over the years in many different grades from weeds to elite rugby and I have never seen it penalised.
I fully appreciate what you are saying Ian, and you are very much in the camp that if the laws don't mention it then it is allowed.
All I can say is that in my experience and part of the world-
- I do not know of any coach that coaches dragging out of the ruck. This is because they know they will be penalised.
- Players that notice somebody lying where they should not be tend to point it out to the ref and expect something to be done about it.
- If it is done then the referee gives a management word to stop it or does penalise it.
- Players that I observe expect it to be penalised. If the referee doesn't then we have an opportunity for conflict which nobody wants.
- If a ref didn't penalise it then I would mention it in the report at the same time as probably making a comment about not dealing with the player lying on the floor.
- Lastly, why should a player need to do it if the referee is doing his job correctly and accurately?
Perhaps it is a North H/South H thing. But I must admit I do not see it when the SH teams play NH teams.
