This comes after he was sent off for dissent during Northampton's Aviva Premiership final defeat against Leicester at Twickenham.
The Saints captain was dismissed for allegedly calling referee Wayne Barnes a "f****** cheat" shortly before the interval in Leicester's 37-17 victory at Twickenham.
On Saturday night the Rugby Football Union announced they would hold a disciplinary hearing into the allegation on Sunday morning.
A statement released by the RFU read: "Hartley was sent off for alleged verbal abuse of a match official contrary to Law 10(4)(s) in the Aviva Premiership final against Leicester Tigers at Twickenham Stadium.
"The case will be heard by a panel chaired by His Honour Judge Jeff Blackett and the result released electronically following its conclusion."
The minimum ban for swearing at officials is six weeks but Hartley has insisted, via Saints director of rugby Jim Mallinder, that his comments were aimed at Leicester hooker Tom Youngs.
The Lions confirmed to Press Association Sport that if Hartley is unavailable for their second tour match, against Western Force on June 5, then he would be replaced in the squad.
A Lions spokesman said: "Warren Gatland has always indicated that these players (competing in Premiership and PRO12 finals) would not play in the first match against the Barbarians but they would have to be available for the second match of the tour.
"That is the criteria for Hartley coming on tour. If he gets a suspension that prevents him from making that second game then that is where we are."
Ireland hooker Rory Best would be favourite to replace Hartley in the Lions squad, should that situation occur.
Northampton coach Jim Mallinder said Hartley's version of events was backed up by a number of other senior players.
"I asked Dylan at half-time and I've just asked him again 'what happened? What did you say?' He said he was talking to Tom Youngs.
"If you talk like that to a player I wouldn't expect anything to happen. Clearly, Wayne Barnes has believed Dylan has spoken to him.
"I support Dylan. He is my captain. If he says he wasn't speaking to the referee and he was speaking to a player on the floor I can only support what he says."
Mallinder continued: "We will support Dylan. He said that a number of senior players that were around the ball agreed with Dylan that he was looking down and speaking to Tom Youngs.''
At the end of an incident-packed final, Leicester were crowned champions after holding off a spirited Saints comeback and Mallinder described the red card as a key turning point.
The Northampton boss referred to an interview Barnes did earlier in the week in which he said the aim for officials is "not to be noticed".
"I feel sorry for him (Dylan) and for the team," he said.
"It was a massive turning point. I read Wayne Barnes didn't want to be the referee to make a decision - he wanted the rugby to determine who won the game.
"It was a massive decision that Wayne made."
Leicester director of rugby Richard Cockerill said: "We know how Wayne Barnes likes to referee. He likes to be treated with respect.
"To be fair, in a game as big as this you would imagine Wayne would be 100 per cent in what he is thinking. I don't want to see a bloke sent off the field.
"Barnes is a very experienced referee, he is one of the top two or three in the world I am led to believe, that is why he gets these games.
"There has been enough history between Northampton and Leicester to know that discipline will be a key part to the game.''
The Hartley incident was not the only moment of controversy in the game. Toby Flood, the Leicester captain, failed to see out the first half after suffering concussion in a tackle from Courtney Lawes.
Barnes penalised Lawes but did not show him a yellow card. Tigers coach Richard Cockerill was furious, arguing it could have deserved more and that the decision should have been referred to the television match official.
At half time, Northampton assistant coach Dorian West told ESPN that Cockerill had been "intimidating" match officials, although Mallinder said he did not believe that exchange influenced the Hartley decision.
Cockerill said: "They were calling for a spinal board because our player has been hit late. I was saying to the fourth official 'surely we need to go to the TMO'. I said the same to (referees' chief) Ed Morrison.
"We used the TMO the whole season. It has been called foul play, we get a penalty so it is clearly foul play, it is late and you have broken an international fly-half who is very important to our game.
"For me, that is the sanction of a yellow card and potentially more. A guy has had to leave the field because of that incident.
"So it is okay to hit players late and it is okay to leave the field concussed is it? I am protecting my players.
"I am allowed to talk to the officials. When a player of ours is potentially seriously injured I will talk to whoever I want.
"How Northampton decide to behave is up to them. I didn't ask anybody to hit anybody late. I didn't ask anybody to swear at anybody, did I?
"Before they make any smart-arse comments about me, maybe they want to look at themselves because my players weren't accusing the referee of anything or hitting people late."