The Toulouse forward, alleged to have entered a seating area during the 28-13 victory over Ulster before punching the supporter, was due to attend an independent hearing in Dublin last Thursday.
But legal teams for the player won a 24-hour injunction at the city's High Court on the grounds the outcome of the hearing could prejudice any criminal proceedings in France and affect Brennan's right to silence.
Last Thursday, lawyers for both Brennan and the European Rugby Cup (ERC) agreed a hearing would go ahead tomorrow - but only on whether or not it would prejudice a case in France.
The 33-year-old is accused of entering the seating area during the game and punching Patrick Bamford, leaving the 25-year-old accountant requiring medical treatment at the ground and on his return home to London.
Brennan, who had already announced his retirement at the end of the season, claimed he was provoked by derogatory chants during the game.
Bamford revealed on Wednesday he has had instructed a French lawyer to pursue criminal and civil proceedings against Brennan.
He is also taking libel action against a number of news organisations which reported the incident.
ERC have stated that tomorrow's disciplinary will convene "to consider preliminary matters raised by Trevor Brennan's representatives concerning the misconduct complaint".
The committee will be chaired by HH Jeff Blackett (England) and will also comprise Rod McKenzie (Scotland) and Achille Reali (Italy).