Offside at the ruck - May 2014
When a scrum half attempts to retrieve the ball from a ruck, the ball is not out until that player has picked the ball up from the ground.
In the clip the scrum half is taken out by the player before the ball is off the ground and this would be deemed to be offside by the player tackling the scrum half. If, however, the scrum half had picked up the ball and a defending player tackles the scrum half, that player does so without sanction.
Footage courtesy of BBC Sport