Federal Authorities Shut Down 'Legal' Medical Marijuana Providers in California

Federal officials in the U.S. have shut down 139 medical marijuana outlets in San Diego amid threats of criminal prosecution.

The U.S. Attorney's office and U.S. Drug Enforcement Administration led the crackdown on dispensaries that are approved under California law, but illegal in the eyes of federal agencies, the San Diego Union-Tribune reported Tuesday.

Of the 222 medical marijuana outlets in the city, 139 had closed after the federal threats. Authorities expected a further 20 to shut down in the coming two weeks.

Alex Kreit, a professor at San Diego's Thomas Jefferson School of Law, doubted the move would eradicate medical marijuana from the city.

"If you only had 10 places operating and you prosecute five, the other five are going to close. But if you have 200 and there's still 100 operating after these letters, well, the letters clearly haven't worked," he said. "I think that the places operating now are assuming that there's probably going to be a few federal prosecutions, and they are just keeping their fingers crossed hoping that it's not them."

California approved medical marijuana 15 years ago, but the drug is still illegal under federal law.