Rugby union has been adept at law trial for decades, but the proposition to bring 20-minute red cards into the game was a point of disagreement between leading players on Tuesday.
On Monday, the French Rugby Federation (FFR) and the body running the top two leagues in France, the National Rugby League (LNR), voiced their concern with the idea.
The sport's global governing body World Rugby trialled the change in the Rugby Championship earlier this year, allowing a team to replace a red-carded player after 20 minutes in the sin-bin.
National unions in South Africa, Australia and New Zealand back the proposal.
"The only way I can look at it is it probably devalues the red card," Wales lock Dafydd Jenkins told reporters.
"There are pros and cons to both of them, but I think we're trying to change rugby so much.
"It doesn't need to be changed," the Exter forward added at the launch of this seasons Champions Cup.
The French players' union, Provale, supported the two other organisations from the country, claiming there lacked sufficient evidence to continue with the idea.
They argued the change would incite dangerous play and, according to the trio, only 60% of teams to have received a red card across a sample of 480 games in the Top 14 and international games lost the match.
"I think it's back and forth between player safety and not wanting to ruin a game if there's one or two reds early in the game and for a big spectacle it can have a big effect on a game," Ireland No 8 Caelan Doris said.
"I think it's a good idea to trial it," he added.
Head injuries have become a sensitive subject in recent years after a group of former players announced they were suing World Rugby.
The individuals allege not enough was done to protect them in their playing days.
"In my opinion you have to look after lads' heads," Ireland winger Jacob Stockdale said.
"The downside of that is that with stricter, tough laws and tougher refereeing you're more likely to get more red cards.
"A lot of the time, a red card can ruin a game," he added.
La Rochelle's Samoa centre UJ Seuteni has been handed four yellow cards and one red during his career.
In the 2021 Top 14 semi-final loss to Toulouse he was sent off for making head contact with Toulouse's fly-half Romain Ntamack during a tackle when the midfielder was at Bordeaux-Begles.
"I think it's a good concept for the game. With the strict rules of the head-on-head collisions," Seuteni said.
"You don't go out there to get red cards but there are situations where red cards are questionable.
"It gives an opportunity for the game to continue to be exciting.
"Red cards, yellow cards, these days are crucial and cost you a lot in a game," he added.
In attempt to improve player safety, World Rugby has reduced the legal tackle height in recent years as the sport is played at a more increased pace.
"Everything happens in less than a second," Racing 92 full-back Tristan Tedder said.
"Players are trying to win momentum, by doing that you have to go low, so everyone drops their body height but tacklers are also already trying to lower their body height but it's still potentially get a knock on the chin, or the head or the shoulder.
"It is hard," he added.
The results of the trial will be studied by World Rugby's executive board and council and put to a vote on November 14.
If it is approved, the change could come into force on January 1.
