As a lifelong conservative, I’m no fan of government regulation. Even so, I’m convinced it’s time for California to aggressively regulate the medical marijuana industry.

I’ve spoken with concerned citizens, local government officials, rural law enforcement officers, federal officials, anti-drug crusaders and medical marijuana industry insiders.

I visited the Emerald Triangle with fellow Board of Equalization member Fiona Ma. Our April tour showed how we can work with the industry to generate greater voluntary compliance with California law.

The current cash-based system is dangerous. Crime, corruption and tax evasion are far too common. Murder and armed robbery rates in California’s rural counties have skyrocketed as the cannabis industry has grown. The FBI and U.S. attorney are investigating and prosecuting local law enforcement officials at staggering rates for taking cash bribes.

These problems stem in part from ongoing conflict between state and federal laws. Nearly 19 years ago California voters approved...