Update 8.50pm: Sam Cane has avoided punishment for the challenge that ended Robbie Henshaw's autumn series.
The Leinster centre was stretchered off after the All Blacks' shoulder made contact with his head, causing him to be knocked unconscious.
A disciplinary committee has judged the incident to be accidental, warranting no ban.
Original story: Disciplinary chiefs have admitted that Malakai Fekitoa should not have been on the field to score the winning try in New Zealand's 21-9 victory over Ireland.
All Blacks centre Fekitoa has been suspended for one week for his high tackle on Simon Zebo that only drew a yellow card in Saturday's feisty Dublin clash.
Referee Jaco Peyper merely sin-binned Fekitoa in a controversial match that later drew 12 citing referrals, 11 pertaining to All Blacks players.
Fekitoa scored two of New Zealand's tries, but avoided a red card that disciplinary bosses have now conceded should have been issued.
"The disciplinary committee found that Fekitoa's actions would have warranted a red card, albeit that he had acted recklessly rather than intentionally," read a statement from the autumn international disciplinary authorities.
New Zealand flanker Sam Cane was also up before a disciplinary hearing on Tuesday, for the high tackle that left Robbie Henshaw unconscious but was only punished by a penalty on Saturday night.
Team manager Mick Kearney admitted on Monday that Ireland were "disappointed" with the officiating fall-out.
Governing body World Rugby issued a stark warning before the November Tests that any dangerous or head-high tackles would be punished harshly.
Players were warned that red cards could be issued, but New Zealand managed to avoid such censure in their three-try win in Dublin at the weekend.
Tuesday's admission that Fekitoa should have been sent off must act as a source of embarrassment for the game's law makers, and raises further questions about the standard of officiating in Dublin.
Fekitoa will now miss New Zealand's final autumn Test, the clash with France in Paris on Saturday.
"When considering sanction, the disciplinary committee concluded that the offending merited a low-end entry point based on World Rugby's scale of seriousness, which carries a two-week playing suspension," continued the statement on Fekitoa.
"The disciplinary committee further found that there were no aggravating factors and that there were a number of mitigating factors; including Mr Fekitoa's immediate acknowledgement of wrongdoing, his previous clean disciplinary record and his good conduct at the hearing.
"And as such his playing suspension should be reduced to one week.
"Fekitoa is therefore suspended from playing rugby for a total of one week, up to and including Sunday 27 November 2016."