Peter O'Mahony's red card for a reckless tackle in Ireland's Six Nations opener against Wales thrust the topic of head injuries in rugby back to the top of the agenda.
The game's authorities are grappling with how to protect players in an era of pace and power while maintaining the essence of a full-contact sport.
O'Mahony's dismissal in Ireland's defeat in Cardiff on Sunday following a brutal head-high hit on prop Tomas Francis shows that dangerous play will draw tough sanctions.
The uncompromising stance is reassuring for the current generation of players but the issue of concussions is casting a shadow over the sport.
A group of ex-players, including England's 2003 World Cup-winning hooker Steve Thompson, are exploring legal action against World Rugby, England's Rugby Football Union and the Welsh Rugby Union after being diagnosed with neurological conditions.
The basis of the claim is that the governing bodies failed to provide sufficient protection from the risks caused by concussion.
Rugby bosses have not commented on the specifics of the legal case but said in a joint statement that they take player welfare "extremely seriously".
- Emotive topic -
World Rugby chief medical officer Eanna Falvey told AFP that concussion is an emotive topic but one the authorities took seriously.
"This is a complex area with many facets, but rugby is progressive, evidence and science-based, and our processes and protocols are regarded as leaders in sport," he said.
"There are many unknowns when it comes to the long-term effects of concussion in general, which is why we take a prevention-first approach."
The former Ireland and British and Irish Lions doctor said the onus was on World Rugby to base decisions on hard evidence.
"Unfortunately a lot of the upsetting and scary stories which are published tend to drive the narrative, to inform the debate," he said.
"We need evidence where there are gaps to fill and that is where we are at the moment."
Falvey points to the high tackle framework introduced in 2019 as an example of the prevention-first approach that rugby has adopted.
"It has provided a uniformity of refereeing across the game," he said.
"It helps coaches and players understand the best technique of tackling for both the ball carrier and tackler, to move from a higher-risk upright position to a lower-risk lower one."
Falvey also cited the Head Injury Assessment, introduced to determine whether or not a player is suffering from concussion and can return to the field of play.
"If you take the player away from the cauldron of play in the 70th minute into a quiet dressing room the player behaves very differently and has a very different opinion when he has settled down," he said.
"To say it was a sea-change is an understatement. It demonstrates how the sport has moved with the science."
- Game-changing tech? -
One potential game-changer could be the PROTECHT gumshield developed by Wales-based Sports and Wellbeing Analytics (SWA), which provides data on the frequency and intensity of head impacts.
World Rugby has supported research into the tool and Falvey said he was encouraged by the progress that had been have made.
"A well-fitted instrumented gumshield in your mouth is the closest you will come to having a microchip implanted in you," he said.
"It is a way for us to measure what the data on head impacts looks like and put a real number on it."
English Premiership side Gloucester are using the gumshield in training.
"This tool can be really useful in identifying impacts which may result in a concussion that may occur out of view, for example the bottom of a ruck," Eoin Power, the club's head of medical services told AFP.
"We have used GPS and video footage to monitor collisions in games but this tool registers contacts and the direction of these forces more accurately.
"Although it is in its infancy, the early data is exciting and extremely valuable."
David Allen, executive director at SWA, said the cost to clubs was minimal compared with the potential benefits to players' long-term health.
The cost is £1,000 ($1,370) per player per season for a rugby club and £2,000 per player per season for a football club.
"It is not a one-off look at a player, it can be weekly, monthly or his whole career and he ends up with a medical passport," he said.