Predictably, the czars' opposition is out of step with voter sentiment on the issue -- which according to the latest data shows Californians supporting the measure 51 percent to 37 percent.

So just what would Prop. 19 do?

According to an assessment by the independent California Legislative Analyst's Office , the immediate effect of the measure would be to allow adults age 21 and older to possess and grow limited amounts of marijuana in the privacy of their own home. The agency estimates that halting the prosecution of these minor marijuana offenses would save state and local governments "several tens of millions of dollars annually," and enable law enforcement to reprioritize resources toward other criminal activities.

The longer-term impact of Proposition 19 would be to enable "local governments to adopt ordinances and regulations regarding commercial marijuana-related activities." These activities would include taxing and licensing establishments to produce and dispense marijuana to persons 21 and older. By doing so, "state and local governments could eventually collect hundreds of millions of dollars annually in additional revenues," the office estimates.

Predictably, critics of Proposition 19 have tried to paint a much more foreboding picture. For example, California senior Sen. Dianne FeinsteinDianne Emiel FeinsteinF-35 fighter jets may fall behind adversaries, House committee warns Warren, Daines introduce bill honoring 13 killed in Kabul attack Democrat rips Justice for not appearing at US gymnastics hearing MORE claims that the measure is "a jumbled legal nightmare that will make our highways, our workplaces and our communities less safe."

Not so, says the Legislative Analyst's Office, which calls Feinstein's fears about pending workplace and roadway calamities unfounded. States the office: "(T)he measure would not change existing laws that prohibit driving under the influence of drugs or that prohibit possessing marijuana on the grounds of elementary, middle, and high schools. "... (E)mployers would retain existing rights to address consumption of marijuana that impairs an employee's job performance."

Sen Feinstein and the drug czars' other primary claim -- that Proposition 19 will dramatically increase consumption and cost the state millions in health and social costs -- ring equally hollow.

Right now virtually anyone in California who wishes to obtain or consume marijuana can do so, and it is hard to believe that adults who presently abstain from cannabis would no longer do so simply because certain restrictions on its use were lifted. In fact, in the years following Californians decision to legalize the medical use of marijuana in 1996, the state has seen a dramatic decline in marijuana use by young people.

Finally, unlike alcohol and tobacco -- two legal but deadly products -- marijuana's estimated social costs are minimal.

According to a 2009 report by the Canadian Centre on Substance Abuse, health-related costs per user are eight times higher for drinkers than they are for those who use cannabis and are more than 40 times higher for tobacco smokers. It states, "In terms of (health-related) costs per user: tobacco-related health costs are over $800 per user, alcohol-related health costs are much lower at $165 per user, and cannabis-related health costs are the lowest at $20 per user."

A previous analysis commissioned by the World Health Organization agreed, stating, "On existing patterns of use, cannabis poses a much less serious public health problem than is currently posed by alcohol and tobacco in Western societies."

So then why are Sen. Feinstein and the drug czars so worried about adults consuming it in the privacy of their own home?

California lawmakers criminalized the possession and use of marijuana in 1913 -- a full 24 years before the federal government enacted prohibition. Yet right now in California, the state Board of Equalization reports that some 400,000 use marijuana daily. Self-evidently, cannabis is here to stay.

It's time to reject the drug czar's tired rhetoric, and abandon the failed federal policy of criminal marijuana prohibition. Let's stop ceding control of this market to unregulated, untaxed criminal enterprises and put it in the hands of licensed businesses. Let's stop sanctioning adults for private behavior that is engaged in absent of harm to others. Let's begin to regulate the use, production, and distribution of pot like alcohol -- complete with common sense controls regarding who can legally produce it, who can legally distribute it, who can legally consume its, and under what circumstances is its use lawfully permitted. Proposition 19 is a first step in this direction.

Paul Armentano is the Deputy Director of NORML, the National Organization for the Reform of Marijuana Laws (NORML) , and is the co-author of the book Marijuana Is Safer: So Why Are We Driving People to Drink?