When is a HIA not a HIA?
Johnny Sexton stole the headlines after Ireland's dramatic Six Nations win in France on Saturday, but when the dust settled another talking point entered the narrative.
Teenage out-half Matthieu Jalibert and scrum-half Antoine Dupont, who had come on for Maxime Machenaud, both left the field with what appeared to be knee injuries, but their replacements went down as HIAs.
This meant that when Dupont went off France were able to bring No 9 Machenaud back on as a like-for-like replacement. This is allowed for a HIA - though Machenaud would not have been permitted to come on if his team-mate went off for a blood or non-head injury.
The Six Nations have said they are investigating the incidents.
Here, the Against The Head panel discusses the flashpoint, with Donal Lenihan commenting: "It is a big deal because the HIA assessment is there for the protection and the welfare of the players.
"The reason it has potential to be abused is because of the law in relation to when a player can come back on to the field."
Watch the full discussion below.