The tip about a backyard marijuana-growing operation set the Pecos Valley Drug Task Force in motion.

Police showed up at the suspect's door in southern New Mexico, ready to make a bust, only to discover he was a patient under the state's medical cannabis program — the first inkling that officers had about legal pot in the area, task force commander David Edmondson said.

"He showed us his permit to grow it, and we left him alone," he said.

But law enforcement agencies in New Mexico and other states with privacy provisions in their medical marijuana laws worry such situations drain their resources unnecessarily and could have a different ending — one in which guns are drawn and someone gets hurt.

Boulder, Colo., police complained last year about their state's grower confidentiality provisions, saying officers spent considerable time investigating operations that turned out to have legal permission to have pot. Providence, R.I., police secretly monitored a suspected dealer, only to find out he was allowed to have marijuana, too.

New Mexico police complain that the state Department of Health, which runs the state's program, should make it easier for them to find out who's licensed to produce medical marijuana in their jurisdiction.

Edmondson said a legitimate grower may not understand who's at the door, and "you could get into a firefight, an officer could get hurt."

Cibola County Sheriff Johnny Valdez agrees. He and other law enforcement officers consider any narcotics report a high-risk situation because illegal producers can be armed or might have booby-trapped the area.

"As far as we are concerned ... we are going into a possible volatile situation. It can go south very quickly," Valdez said.

State Health Secretary Dr. Alfredo Vigil said names of patients and licensed growers are secret from everyone for privacy and safety reasons. Some growers and users in states without confidentiality clauses have been targets of robberies that have resulted in injuries and even deaths.

"Generally speaking, things that are private and confidential in the world are private and confidential from law enforcement as well unless they go through due process," Vigil said.

New Mexico's program, which kicked off in 2008, still is in its infancy, with "many, many unanswered issues and questions we are slowly working our way through," he said. "The relationship with law enforcement is one of those."

The state licensed its first marijuana grower last year; it now has 11 after six were approved in July. In addition, about 1,000 of New Mexico's 2,250 active patients are licensed to grow their own supply.

The Health Department has a 24-hour line police can call to verify someone is legitimately part of the program. It says officers can provide just an address and don't need a name.

The department receives eight to 10 calls a month to verify patients, but has not received any about legal producers, agency spokeswoman Deborah Busemeyer said.

But Darren White, head of the Albuquerque Department of Public Safety, said it's not practical to expect police to call every time they hear about marijuana.

"If we get a tip that there's a marijuana grow, I don't think agents are going to feel comfortable calling someone who's not even law enforcement and asking if they're legit," said White, a former Bernalillo County sheriff and former state Department of Public Safety secretary.