World Rugby move fast to outlaw law exploitation sweeping sport

World Rugby have moved fast to outlaw the latest law loophole being exploited by clubs - issuing an amendment that will come into immediate effect.

Saracens are credited with creating the new loophole known as 'crabbing', a cousin of caterpillar rucking - which still remains legal.

With the caterpillar technique, players join rucks single file, leading to a queue of players behind a ruck. It allows nines to box kick without fear of being charged down by opposition defenders, as they are simply too far away from the scrumhalf to do anything.

Crabbing or 'side ruck extension' is different as it sees the hindmost bound player of a defensive team stay bound but then crab sideways to get closer to the opposition nine, to either disrupt the player or effect a tackle.

The technique was first employed by Saracens but soon spread to the continent, with Castres also crabbing around the side of rucks in the Top 14. World Rugby cites two instances of the practice, providing videos of Saracens Nick Isiekwe and a Castres' player both crabbing around the side of a ruck.

World Rugby have moved to clarify the Laws around the practice, pointing out that players must retreat to the hindmost foot of the ruck.

"Recently there have been instances of rucks being extended sideways which gets the last player very close to the opposition 9 when he/ she is box kicking. This reduces space and the options available to players.

"Adding players to your own side of the ruck, in order to advance closer to the opposition side of the ruck, as shown in the clips attached, squeezes the space available and compromises the clearance of the ball from the ruck.

"These actions should be discouraged.

"If a player is fully bound and they have moved beyond the offside line then they must return to be behind the hindmost foot before being able to be involved in play, once the ball is out or is played from the ruck."