The law, which is being trialled in Super Rugby and was also implemented in the Guinness Pro14 Rainbow Cup last season, means the dismissed player can be tactically replaced by a substitute after 20 minutes.
World Rugby, however, is determined to keep lowering tackle heights and the Super Rugby trial so far has proved inconclusive.
Glasgow Warriors and Edinburgh had a taste of the 20-minute red card during last season’s Rainbow Cup match at Scotstoun when each side had a player sent off. Edinburgh’s Mark Bennett and Glasgow’s Oli Kebble were dismissed but each was replaced 20 minutes later.
The 20-minute red card was one of three law variations trialled in the Rainbow Cup, along with the captain’s challenge and goal-line drop-outs. The latter has now been brought in but the captain’s challenge was dropped.
Regarding the 20-minute red card, World Rugby chief executive Alan Gilpin told the Daily Telegraph: “That’s been discussed before and will be discussed again.
“It would be great if more competitions, even in a closed trial, would use it because that would give us more of an overview of the effect it would have on the game.
“We need to see more of the data to see whether that strikes the balance between safety and spectacle better.
“There is more work to do to analyse that and the concern is, if a team goes back to 15 players, is that enough of a deterrent to drive that behavioural change.
“We would like to see it trialled more widely before drawing any conclusions.”
The 20-minute red card is already available as a closed trial (as per Super Rugby) but cannot be considered for global adoption before the next women’s (later this year) and men’s (2023) Rugby World Cups.
The 20-minute red card was not supported by World Rugby when the global trials were considered back in May 2021, but dispensation was given to any competition wanting to run it as a closed trial.