The England captain was sent off for Northampton on Friday night
England captain Dylan Hartley has been formally cited for his attempt at tackling Sean O'Brien during Friday night's Champions Cup clash with Leinster.
The Northampton hooker, who started the game on the bench, lasted less than ten minutes before getting his marching orders from referee Jerome Garces. O'Brien was subsequently substituted as was unable to continue.
Hartley will go before a disciplinary committee on Wednesday in London to defend himself. According to the citing commissioner, the England captain has broken Law 10.4 (a) striking.
"Under World Rugby's Sanctions for Foul Play, Law 10.4 (a), Striking a player with a hand, arm or fist carries the following sanction entry points - Low End: 2 weeks; Mid-Range: 5 weeks; Top End: 8 to 52 weeks.
Due to Hartley's previous disciplinary issues, he may face a ban in the top end of the scale, if found guilty. Over the course of his career he has been banned for 54 weeks for a number of incidents, including making contact with the eye area the then Wasps player Johnny O'Connor. He was also previous banned for biting Stephen Ferris.
The ban may also determine the immediate future of his international career. Hartley's England captaincy may also be on the line if he misses some of the games in February and March.
In 2013, after being picked for the Lions tour to New Zealand, Hartley was banned for 11 weeks, after verbally abusing the referee during the Premiership Final. He subsequently missed the tour.