City Attorney Mike Feuer announced that a Los Angeles city crackdown has prompted more than 500 medical marijuana shops to close down in less than two years, According to the report in the Los Angeles Times, that represents a jump from a year ago, when Feuer reported that about a hundred pot shops had been shuttered. The city attorney has also targeted other ways medical marijuana has been distributed, securing court injunctions against a Boyle Heights pot farmers market and a smartphone app used to arrange pot deliveries.”There are a whole bunch of different vehicles that we pursued to close them,” including civil and criminal cases and warning letters, Feuer said. “We’ve made tremendous progress.”

Still, the city doesn’t know how many marijuana businesses continue to operate, raising concerns from critics that the crackdown may amount to a game of whack-a-mole.Under Proposition D, approved by voters two years ago, pot shops and the landlords that lease them space can be prosecuted if the businesses don’t meet a number of requirements. Those include being registered under past L.A. ordinances and operating a specified distance from public parks, schools and other facilities.

When the restrictions were approved, city officials estimated that fewer than 140 medical marijuana dispensaries would be eligible to remain open and avoid prosecution. At the time, police officials said they believed roughly 700 pot shops were operating, although some estimates put the figure more than twice as high. Feuer said neighborhood complaints about the city failing to tackle illegal shops, which he routinely heard when he was first elected two years ago, are now much less frequent. “We are shutting down unlawful dispensaries at a rapidly increasing pace,” he said. That “momentum” will make new, unlawful shops reluctant to open in Los Angeles, he said.

Last year, more than 450 medical marijuana shops filed tax renewals to report their gross receipts, according to the Office of Finance. The number appears to have fallen slightly this year, with 415 businesses renewing around the March deadline. But it isn’t clear if the tax numbers account for all shops. Hundreds more marijuana businesses – more than 1,100 dispensaries – are still registered on the books to pay business taxes, though city officials say many of those may have closed without telling the finance office.

Another estimate by UCLA researchers, who canvassed addresses they found online and through city registrations, found 418 marijuana businesses operating in L.A. last year – more than three times the number supposedly allowed. That was only a slight decrease from two years earlier, when a similar survey found 476 shops. The UCLA Medical Marijuana Research team also found that marijuana shops have been shifting from the San Fernando Valley and East L.A. to South L.A. and San Pedro. Principal investigator Bridget Freisthler said it’s unclear why. It “might be in response to community efforts to close some dispensaries,” she said.

San Diego reports a similar struggle to control the number of shops. In four years, more than 200 of the dispensaries have been shut down, with 40 more awaiting enforcement, according to the city attorney’s office. All opened during the time when the city had no zoning that would permit marijuana dispensaries. The San Diego City Council in July adopted a medical marijuana ordinance allowing no more than four dispensaries in each of the nine council districts. A dozen applications are being reviewed. “Our aggressive enforcement of city zoning regulations is necessary to protect neighborhood standards and safety,” said San Diego City Attorney Jan Goldsmith.

Medical marijuana is an $18 million dollar tax boon for the City of San Jose, but two of the South Bay’s largest dispensaries are now in a conflict with city leaders. In February, the Investigative Unit revealed that some San Jose pot shops owe millions in unpaid marijuana taxes. In that story, San Jose Mayor Sam Liccardo sent a message to the owners of Medimarts in East San Jose and All American Cannabis Club in West San Jose, “Pack up, it’s time to move on and pay up on your way out,” said Liccardo. Dave Armstrong, President and CEO of Medimarts, said the Mayor’s tough talk creates puts him between a rock and a hard place. “The city wants us to do something, but on the other hand it’s illegal,” said Armstrong.

Armstrong argues that by paying the city’s Marijuana Business Tax, he’s also admitting to selling a federally banned substance. “So which of is the worse of the two?” he said. “Breaking federal law or breaking a municipality ordinance?….It’s where we’ve been for three years.” The All American Cannabis Club (A2C2) in San Jose makes the same argument” Founder Dave Hodges said the city is using back door tactics to shut him down.

Many cities have banned cannabis dispensaries, while others tax and regulate collectives operating out of retail storefronts as well as cultivation. The federal government has a history of threatening California city council members, county supervisors, and government staffers with drug trafficking charges if they seek to regulate medical cannabis cultivation or distribution. Federal prosecutors have shut down cultivation regulation programs in Humboldt County and Oakland.