IRFU and other unions veto proposals to introduce radical new law surrounding red cards
Controversial proposals to downgrade the severity of red cards have been vetoed by the four home unions, the PA news agency understands.
England, Wales, Ireland and Scotland rejected out of hand suggestions to alter the punishment meted out for red cards in time for the World Cup, that kicks off in Japan on September 20.
World Rugby is understood to have held a conference call with top figures across the game where plans to dilute red card sanctions were seriously discussed.
Some of the game's top decision-makers weighed up allowing a player awarded a red card to be dismissed - but then be replaced by a substitute 15 minutes later.
That radical alteration would have left teams receiving red cards playing with 14 men for just five minutes longer than a yellow card sin-binning, then being restored to a full complement.
World Rugby has eventually implemented a new procedure where the Television Match Official (TMO) must now be consulted over all potential red-card decisions.
World Rugby confirmed that protocol amendment on August 30, which will now be in effect for the World Cup.
New Zealand were left frustrated by Scott Barrett's red card in their 47-26 defeat by Australia in Perth on August 10.
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Barrett was sent off for a shoulder charge to Michael Hooper's neck, but All Blacks bosses were frustrated by the decision.
A number of top figures in the game have raised concerns over the interpretation of punishments for high tackles, with some worried any increase in red cards could damage the World Cup.
England boss Eddie Jones warned last month that the World Cup could be "destroyed" by inconsistent refereeing.
World Rugby held a conference call where plans to alter punishments for red cards in time for the World Cup were floated.
But the four home unions are understood to have quashed any tentative blueprints for radical change.
World Rugby was contacted for comment and would not discuss specifics of negotiations, but pointed instead to that new process where any potential red-card decisions must be ratified by the TMO.
World Rugby issued new high tackle punishment decision-making framework for referees back in May, designed as another boost to player welfare and to simplify the process of disciplining foul play.
"World Rugby is committed to player safety and we collaborate with coaches, players and match officials on all player welfare matters, including the implementation of the high tackle sanction framework, which has been implemented after extensive trials demonstrating concussion reduction benefits," said a World Rugby spokesman.
"The inclusion of the TMO to aid referee decision-making in the implementation of framework for occasions of dangerous foul play is a common-sense addition, enabling the match official team to make full use of the advanced Hawkeye technology available at Rugby World Cup to further support clear and consistent decision making in this important area of the game."