Worcester Warriors forward Phil Dowson has seen his charge for striking Saints wing Ken Pisi with an elbow during Saturday's game at Franklin's Gardens dismissed.
Dowson, who will be retiring this summer and returning to Northampton as an assistant coach, caught Pisi during an aerial collision in the first half of the Aviva Premiership game.
Replays were shown on the big screen, with Saints fans unsure whether to boo their former player and future coach.
Referee Craig Maxwell-Keys decided that Dowson deserved to concede a penalty but no further action was taken.
Saints went on to win the game 24-14 thanks to two tries from Mike Haywood and one from Teimana Harrison.
Dowson, who made 186 appearances for Saints between 2009 and 2015, attended an RFU disciplinary hearing in Coventry on Wednesday evening.
And it was decided that the player should not be punished, meaning Dowson is free to play again with immediate effect.