Hartley said it was right players were left to decide for themselves.
The Sun tabloid alleged Manchester United forward Rooney drunkenly gatecrashed a wedding at England's hotel in Watford, north of London, on Saturday.
Rooney started England's 3-0 World Cup qualifying win over Scotland on Friday, but suffered a knee injury that ruled him out of Tuesday's 2-2 friendly international draw at home to Spain.
A statement issued on Rooney's behalf, said he was sorry the pictures had been published and accepted the images were "inappropriate for someone in his position".
That prompted England football chiefs to announce a review of their policy regarding players' time off.
But Hartley, speaking at the England rugby squad's hotel in Bagshot, southwest of London, ahead of this weekend's Twickenham international against Fiji, said it was right players were left to decide for themselves.
"If you treat men like men, you get men," he insisted.
Hartley knows about the unwanted fall-out from alcohol-fuelled incidents.
The hooker was of the England players who ended up in a bar featuring dwarf-tossing on a drunken night out during the 2011 World Cup in New Zealand.
That led to calls for a curfew, but Hartley said the current squad were managing just fine without one.
"We police ourselves and we trust individuals to make the right decisions," he said.
"That is how our team operate.
"If you're alluding to what we are going to do after the Fiji game, we have got another Test match (against Argentina) to get ready for," added Hartley, who stressed players could still have a "couple of beers" between games.
"Our culture this year has loosened, said Hartley in a reference to the regime of former coach Stuart Lancaster -- who dropped him from the squad for last year's World Cup in England on disciplinary grounds.
"We have gone the other way. We just trust in the guys to make good decisions. We don't have an A4 sheet with rules written on it.
"Luckily we haven't had any issues as of yet."
Earlier, England coach Eddie Jones, Lancaster's successor, said he had no qualms in trusting his side.
"They are adults," he said. "Most of the players have got their own families.
"They'll come back here, they'll have a few beers and they'll decide when they go to bed."
The Australian added: "The time we have to have a curfew is the time we don't have a leadership group within the team.
"I generally like the players to set the regulations because then it's self-policing.
"Most teams I've had have never set curfews," the former Australia and Japan coach recalled.
"They are professional sportsmen who have the privilege of playing for England.
"They have to do everything to be at their best for England. If they do anything outside of that, then they don't want to play for England."
Interim England football manager Gareth Southgate, still waiting to discover if he will be appointed on a full-time basis, said there was a need to review how the national team's players spent their free time.
"They trained Saturday morning and they trained again on Sunday afternoon, and I gave the players a period of time off (in between)," Southgate told reporters after the Spain match.
"I'm not aware of anything else.
"There were lots of changes we made to routines. Some things we thought we should keep the same and I'll have to review (it) -- or maybe I won't have to review! Someone will have to review it."