Williams was shown a red card by referee, John Lacey, in the 24th minute of the Cardiff Blues v Montpelier match for an alleged dangerous tackle on the Montpellier scrum half, Benoit Paillaugue
The Blues scrum half will now travel to Dublin on Thursday for the hearing. Jeremy Summers (England) has been appointed as the independent Judicial Officer for the hearing. The decision will be communicated in advance of this weekend's Round 4 matches.