Shane Jennings has been banned for 12 weeks after being found guilty of eye-gouging London Irish lock Nick Kennedy.
The Leinster flanker was cited following te defending champions' 12-9 Heineken Cup defeat to London Irish on Friday night in Dublin.
Kennedy reacted furiously to the incident during the game and accused Jennings of poking a finger in his eye, although he later claimed to have over-reacted.
At a European Rugby Cup Ltd disciplinary hearing in Dublin today, Jennings was found guilty "of an contrary to good sportsmanship in that he made contact with the eye or eye area of Nick Kennedy".
The judicial officer Roger Morris from Wales decided the offence was at the low end of the scale and, having taken into account any mitigating and aggravating factors, he banned Jennings until January 6, 2010.
Both parties have the right to appeal.