Is a player offside if, although his feet are on side, he has a hand in contact with the ground ahead of the offside line?
Law 15.4 Each team has an offside line that runs parallel to the goal line through the hindmost point of any ruck participant.
Using this logic/reasoning, the picture clearly shows that the Black player in a three point stance is offside – purely from his feet position – and liable to sanction.
A ruck/maul defender making contact by hand with the ground ahead of the offside line renders such a player offside – even if his feet are onside and carrying his weight.
Hence should a defender have both feet behind his/her offside line and no other part of his/her body on the ground (i.e. they are demonstrably self-supporting entirely on their feet), then they may have torso, shoulders head or arms over the plane of the offside line, but a three point stance with the hand on the ground over the offside line can be justifiably sanctioned.
If his feet were on side and didn’t move, could he lift his hand from the ground and not fall over? Some will say “yes” and some will say “no” bringing in the need for a judgement call.
At the top level nowadays referees penalise a post tackle arriving player who puts his hands on the ground before grabbing the ball – often as he’s cleared out himself. (Law 13 Principle.).
Law 13.3: A player on the ground without the ball is out of the game and must (c) Not tackle or attempt to tackle an opponent.
The pictures supporting the offside law (within the various sections of the Law book) show that this applies to both feet, but only show any such player in a “two point” stance (i.e. feet only in contact with the ground), but can show such a player with their hands on his/her own knees and this may well bring that player’s torso over the plane of the offside line.
Should that player attempt to tackle an opponent by lifting the hand and driving forwards and if lifting the hand and stepping forward (when legal to so) restores the player to his/her feet, then a penalty is hard to justify as that player has started entirely from an onside position and got back to his/her feet before attempting that tackle.
Response written December 21st, 2018 – updated 6th January 2019.