Three of Saints' key players - Chris Ashton, Tom Wood and Phil Dowson - will appear before Rugby Football Union disciplinary chiefs in London on Tuesday.
Saints resume the Heineken pool phase against French club Castres next weekend, having suffered successive European defeats to Munster and the Scarlets.
Another loss would effectively dump them out of quarter-final contention.
England wing Ashton has been cited for an act contrary to good sportsmanship, the RFU announced.
The complaint, lodged by citing officer Mike Rafter, is that Ashton pulled Leicester wing Alesana Tuilagi by his hair and dragged him from the field of play during Northampton's Aviva Premiership defeat against the Tigers at Welford Road three days ago.
Ashton's action sparked a touchline brawl that ended with referee Wayne Barnes sending off Tuilagi and Wood.
Tuilagi and Wood were both dismissed for striking, although Barnes took no action against Ashton.
Wood's back-row colleague Dowson has been summoned after being cited for a dangerous tackle on Saracens back Alex Goode in a Premiership game at Franklin's Gardens 10 days ago.
Ashton, Wood and Dowson could all be banned as Northampton approach a busy period of games that sees them playing Castres home and away, followed by Bath on Christmas Eve and Newcastle on New Year's Day.
No other citings, though, have emanated from the Northampton versus Leicester incident despite several players from both sides being involved.
The RFU hearing will be chaired by Twickenham disciplinary chief Judge Jeff Blackett, assisted by Jeremy Summers and Christopher Quinlan QC.
Dowson is scheduled to start proceedings, followed by Ashton, then Wood and finally Tuilagi.
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