Thanks to the Election Day ballot measure, marijuana use will be treated much the same as alcohol in California. Just like having an open container will result in a ticket (at least), smoking weed while driving is definitely not allowed. That goes even for drivers with a medical marijuana license. And while Proposition 64 legalizes recreational marijuana in California, the law against toking it up behind the wheel remains unchanged.
Medicinal marijuana has been legal in the Golden State since 1996. Interestingly, using weed while operating an automobile has always been against the law in California, even if the driver is using for medical reasons. Research indicates that pot consumption does impair driving, especially when combined with even low amounts of alcohol.
Marijuana usage while driving is illegal in all 50 states, and Proposition 64 keeps that prohibition in place for California drivers. Voters passed the ballot measure Nov. 8, making recreational use of weed legal under certain circumstances. Those over the age of 21 who are so inclined can smoke at home or at a business established for the purpose of marijuana consumption. Public places and anywhere that smoking cigarettes is prohibited (which describes a lot of California) are, however, off limits for anyone looking to smoke weed.
Alaska, Colorado, Oregon, and Washington have already made weed legal in their states. It will be interesting to see if the trend continues up to the federal level. Under current law, marijuana is still a federally prohibited, Schedule I substance.
Though the Obama administration made clear they were not going to prosecute states that passed marijuana legalization, the future of this tension between state and federal laws will likely play out for some time. As recently as August, the Drug Enforcement Agency (DEA) stated it had no intention of declassifying marijuana as an illegal drug, citing a Health and Human Services evaluation that says:
... The drug’s chemistry is not known and reproducible; there are no adequate safety studies; there are no adequate and well-controlled studies proving efficacy; the drug is not accepted by qualified experts; and the scientific evidence is not widely available.
But as national opinions shift about marijuana, with much of the stigma previously attached to the drug now gone, it may be that Congress will be faced with some kind of vote in the coming years. As of right now, Colorado is being sued by two nearby states, Nebraska and Oklahoma. Both claim that the legalization of marijuana in Colorado has brought a "bootlegged" pot industry into their states. And though the Supreme Court recently declined taking up that case, they may very well be forced to hear a similar case in the near future, as more states confront sharing a border with a weed-friendly neighbor.