In the wake of federal prosecution threats, Kernighan said, "We are in an abundance of caution these days."
So is the city of South Lake Tahoe, which had allowed three dispensaries on Lake Tahoe Boulevard to grow marijuana on site. The city was considering a plan to entice them to move their grow rooms by allowing expanded cultivation in an industrial area away from the lake.
Now, "the memo from the U.S. attorney's office is giving us some pause," said city attorney Patrick Enright.
Yet mega-scale pot cultivation is flourishing in Colorado, which allows dispensaries to operate for profit in contrast with California's nonprofit model.
"We have whopper grows," said Colorado lawyer Warren Edson, whose clients include medical marijuana stores that lease growing space in a 120,000-square-foot indoor farm in downtown Denver.
Edson said he suspects that Colorado hasn't been targeted because unlike California it has statewide regulation of medical marijuana, including licensing of pot industry workers. "We're doing what we're doing and keeping our fingers crossed," he said.
Less than two years ago, Ogden's memo vowed "prosecution of significant traffickers of illegal drugs, including marijuana." But he said the government wouldn't target pot patients or their caregivers "whose actions are in clear and unambiguous compliance with existing state laws."
In his memo, Cole said that policy remains unchanged. But medical marijuana attorney Joe Elford said a series of federal raids this spring on dispensaries in Montana and Washington has unnerved advocates for medicinal use.
Two states that allow medical marijuana, Rhode Island and New Jersey, have refused to permit dispensaries, citing fear of federal action.
"We're concerned for our patients," said Elford, legal counsel for Americans for Safe Access. "The majority of patients obtain their marijuana through dispensaries. Most sick people don't know how to cultivate quality marijuana.
"There is a specter of widescale criminal prosecution. And needless to say, that is very scary for us."