As of December 2018, 10 states (including California) have legalized recreational marijuana in some form or another -- and many people believe that it's only a matter of time before the rest of the nation follows.
If you're a physician, however, none of that means you're actually free to purchase a little marijuana and some rolling papers and light up. What the law says you can do and what the state's Medical Board says you can do -- if you want to keep your license to practice medicine -- may not be the same thing.
The Medical Board of California has not (yet) issued a formal statement regarding the use of cannabis for recreational purposes -- and it probably won't. Its existing policies regarding physicians and intoxicating substances like drugs and alcohol are likely deemed sufficient to cover just about every question that could be raised regarding legal marijuana.
Physicians are generally held to an elevated set of expectations regarding both their professional and private activities. Any action -- no matter how legal -- that could put patients at risk puts a physician's license in danger.
In that regard, recreational marijuana is pretty much like alcohol. The fact that it is now legal in California doesn't change the fact that a doctor has an obligation never to practice medicine while he or she is impaired due to an intoxicating or mind-altering substance. It doesn't matter if that substance is whiskey or weed.
Here's the problem, however, for physicians: cannabis, unlike alcohol, doesn't metabolize very quickly. It can stay in a user's system long after the psychoactive effects have worn off. The Medical Board has declined to state how long a physician has to wait to see patients after using recreational marijuana. Given the way the drug affects different people in different ways, the Board likely can't come up with a definitive answer. Every situation might be different.
For physicians who want to use recreational marijuana, this could present problems. If you have a drink and treat a patient a couple hours later, a blood alcohol test can prove that you weren't impaired. You won't have the same ability with cannabis.
Defending your medical license against allegations that you were impaired while on the job due to drugs or alcohol can be complicated. Don't try to handle your case on your own.