When recreational-marijuana shops open Jan. 1, Denver police officers will stand outside for crowd control but won’t be allowed to step inside to provide off-duty security from within.

A departmental order issued this month bars Denver officers from moonlighting as security guards at marijuana shops while police officials observe how the burgeoning industry develops.

The legalization of recreational marijuana is posing many challenges for the police department as it drafts internal policy to deal with an industry that is still illegal federally.

“We’re going to do everything we can to make sure those businesses are safe, but we’re not going to work inside those businesses,” said Sonny Jackson, a department spokesman. “It’s a new industry, and we’re not sure what it’s going to entail.”

Denver officers earned about $10.6 million dollars between 2009 and 2012 working off-duty security jobs at venues such as bars, sporting events and even many liquor stores. Private businesses pay uniformed officers about $45 an hour to stand armed guard, offering a police presence without draining on-duty resources. But department policy prohibits them from providing off-duty protection to “any establishment which constitutes a threat to the status of dignity of the police as a professional occupation,” including porn stores, strip clubs and nuisance bars.

“This restriction prohibits officers from providing security at any such location and from providing security for the transportation of financial proceeds from any marijuana-related business,” the Dec. 6 memo to all sworn personnel reads. “Officers can expect future revisions regarding policies pertaining to marijuana as the laws are developed and finalized.”

Marijuana shop owners have said officers’ training, skills and uniforms would be particularly effective in protecting their cash-only businesses, which are a prime target for thieves.

“Not only are they trained law enforcement, but they give an air of legitimacy to what we are doing,” said Norton Arbelaez, an owner of the medical-marijuana dispensary RiverRock, who inquired about hiring officers about four years ago and was denied. “We’re drawing a fine line between the illegal and the legal market and what better way to do that.”

Since recreational marijuana was legalized a year ago, marijuana advocates have urged the city and state to treat it the same as alcohol. Denver has about the same number of marijuana dispensaries as liquor stores.

But pot’s status as an illegal federal drug and its stigma for some continue to make that difficult if not impossible for police.

Until last week, Denver police had no written policy about secondary employment at medical-marijuana businesses, but officers never provided such security, Jackson said.

State law prohibits law enforcement officers from owning pot shops, and the department has a zero-tolerance policy on drug use, including marijuana.

The city and its police department are still struggling to decide how strictly to enforce laws against public consumption of marijuana. Earlier this week, the City Council approved rules banning the display or distribution of marijuana on the 16th Street Mall or streets around it and in city parks.

Police Chief Robert White promised the City Council that his department would revamp its marijuana enforcement training.

In recent marijuana demonstrations, police officers have stood by with a hands-off approach.

On-duty officers were called on last month to provide cover when federal agents raided more than a dozen medical-marijuana businesses

, investigating possible ties to Colombian drug cartels.

“Can you imagine a Denver cop in full uniform working at a marijuana dispensary store when the feds come and serve a search warrant?” police union president Nick Rogers said.

The state is under pressure from the federal government to show that it is strictly regulating marijuana — in particular, keeping it out of the hands of children and criminals.

Without police protection, dispensary owners have relied on private security guards, cameras, alarm systems and high-end locks.

“I would hope that the private market would be able to fill this void,” said Denver Councilman Charlie Brown, who led a council committee on recreational marijuana and still has concerns about crime and safety at pot shops.

“This is what I call the fear of the unknown,” he said.

Police say extra officers will be on hand for crowd and traffic control near pot shops opening on Jan. 1.

“If, in fact, a bus shows up with 200 people, there will be a presence there,” White said.

Michael Elliott, director of the Medical Marijuana Industry Group, said police will have to adjust to the new realities surrounding pot.

“These businesses are here, and they’re here to stay. Now the police department should get on board with how best to protect these businesses,” he said. “Moonlighting is one additional way to do so.”

Sadie Gurman: 303-954-1661, sgurman@denverpost.com or twitter.com/sgurman