Listen to this concussion specialist, Dr. Ross Tucker, talk about the Maynard incident, at about 62 minutes in. There is a lot of talk about head injuries, mostly in Rugby Union, starting at 39 minutes in. He says that in Union, there is a duty of care for the other player (I know this has been talked about in the AFL but doesn't apply to Magpie players): https://podtail.com/en/podcast/the-science-of-sport-podcast/rugby-world-cup-23-the-amazing-tech-used-to-look-a/