The activists — who have publicly identified themselves as Sean Devlin and Shireen Soofi — orchestrated the brief protest on Monday at a downtown hotel, where Harper was fielding questions at an event hosted by the Vancouver Board of Trade.
Devlin and Soofi walked into the stage each holding a sign attacking the Conservative's record on climate change before they were swiftly removed and arrested.
They were released a short time later, but the incident raised immediate questions about how a pair of activists could get that close to Harper despite the presence of his personal RCMP security detail.
Vancouver police Sgt. Randy Fincham said that, after consulting with the RCMP and Crown prosecutors, investigators have declined to recommend charges.
"After reviewing what happened and speaking with the RCMP, it was determined that charges were not appropriate in this case," Fincham said in an interview.
"It was determined that it wasn't in the public's best interest to pursue an investigation into criminal charges."
Devlin said when he was released by the police, he didn't believe he would face charges, but he hadn't yet received official confirmation until he was contacted by a reporter on Tuesday.
"I'm certainly happy to hear there aren't going to be any charges," Devlin said in an interview.
The Prime Minister's Office and the RCMP have each declined to discuss what happened, but the Mounties are reviewing the incident.
Devlin has said he and Soofi arrived at the hotel wearing second-hand formal wear they picked up at a thrift store in order to blend in with the serving staff.
He said they weren't approached by security at any point before they walked on stage, which was situated in a large hotel ballroom packed with audience members.
While a police dog went through the equipment of reporters and television camera operators, there appeared to be little outward display of security at the event that would have prevented anyone from walking into the room.
Devlin and Soofi walked onto the stage behind Harper and board of trade CEO Iain Black, who were sitting in lounge chairs for the casual question-and-answer event, before holding up their signs toward the audience.
One sign said Climate Justice Now, while the other said Conservatives Take Climate Change Seriously, with a dark line crossed through the sentence.
The two protesters were hurried away by security. Devlin fell down a small flight of stairs as he was pushed off the stage, while Soofi left on foot.
For his part, Harper appeared unfazed by the interruption, telling the audience: "It wouldn't be B.C. without it."
Devlin and Soofi are affiliated with Brigette DePape, the former page who walked onto the Senate floor holding a Stop Harper sign during a 2011 throne speech.
DePape was immediately fired from her job at the Senate and has since become an activist against the Conservative government. That work has included forming a group with Devlin known as SHD — a profane acronym that roughly translates to Stuff Harper Did.
Devlin said his group had two goals on Monday: to protest the Conservative government's environmental policies, as well as to assert what he described as the public's right to access the prime minister.
"I think part of the reason we felt the need to go into the event was that we find the extent to which this government is really closing itself off — not just from the public, but also from the media — unacceptable in a democratic country," he said.
"We really felt like we were supposed to be there and should be allowed to be there and have access to the prime minister."
Harper's swing through the B.C. was briefly interrupted again on Tuesday as about 100 protesters chanted and waved placards outside Brentwood College in Mill Bay, where he was speaking to Conservative party supporters.
Also on HuffPost