zer0
John Thornett (49)
Brumbies had used all their subs. If someone had broken their leg the same rule would have applied but without the need for an assessment. It’s been that way forever.
Not according to these laws, which, as far as I can tell, are the two relevant laws (and assuming I'm reading them right):
TEMPORARY REPLACEMENT - HEAD INJURY ASSESSMENT (HIA)
3.26. In elite adult matches, which have been approved in advance by World Rugby (pursuant to Regulations 10.1.4 and 10.1.5) for use of the HIA process, a player who requires an HIA:
a. Leaves the field of play; and
b. Is temporarily replaced (even if all the replacements have been used). If the player is not available to return to the field of play after 10 minutes (actual time) of leaving the playing area, the replacement becomes permanent.
TACTICAL REPLACEMENTS JOINING THE MATCH
3.32. Tactically replaced players may return to play only when replacing:
a. An injured front-row player.
b. A player with a blood injury.
c. A player undertaking an HIA.
d. A player who has just been injured as a result of foul play (as verified by the match officials).
e. The nominated player described in Law 3.18 or 3.19.
Nothing there says to me that a tactical replacement cannot return to the field for a who has failed a HIA. Though, equally, there's nothing to explicitly say he can, either, as 3.32c talks about returning for a player undertaking a HIA, but says nothing of what happens should that player fail it.EDIT: Sorry. This only concerns HIA, not regular injuries, for which you are correct. I think 3.32b was at the core of that bloodgate scandal in England a few years ago.