The fact O'Brien left the field for a Head Injury Assessment and did not return following Hartley's reckless challenge certainly won't help the Northampton player. Neither will World Rugby's latest directive for referees and disciplinary boards to come down especially hard on players making contact with other player's heads, recklessly or otherwise.
Eight weeks is the top-end entry point, which could be extended further if Hartley's track record is considered.
European Professional Club Rugby (EPCR), who organise the European Champions Cup, confirmed on Saturday that Hartley's disciplinary hearing will take place within the next five days.
Any remote hope Hartley had of being named captain for next year's Lions tour to New Zealand now appears dead in the water.
Former Ireland and Lions captain Brian O'Driscoll tweeted: 'Mindless from Hartley. Lions Captain???!
Former England player Pat Sanderson said: 'Eddie Jones has got a decision to make because some coaches would not forgive that. We thought Dylan had got this out of his system but clearly he hasn't. With Jamie George playing so well for Saracens, Eddie has a decision to make.'
Hartley's sending-off left Saints a near-impossible mission as they went on to suffer another humiliating defeat which leaves coach Jim Mallinder clinging to his job. With Calum Clark (three weeks for elbowing) and Kieran Brookes (two weeks for reckless contact with head) also serving bans, Northampton's discipline has dropped off a cliff while their form implodes.
Hartley was criticised by former England captain Lawrence Dallaglio, who accused the current skipper of acting in his own interests when playing for Northampton.
'There's no doubt it was a red card,' Dallaglio said on BT Sport. 'It was an unnecessary challenge, a swinging arm. It is reckless and got what it deserved.
'Dylan's sort of checked out of playing for Northampton. He's been brilliant for England. According to Eddie Jones he's been a great leader. But he's checked out of playing for his club and I don't think you can do that.
'I've been captain of England and I know the pressures. It's tough. But when you go back to your club you need to lift spirits, get the banter back and translate that confidence back to your club side. Every time that's been asked of him, he's not done that, he's just looked after number one.'
