On November 2nd, California voters will have an opportunity to legalize marijuana use for all persons over 21 and authorize local government to regulate its use and sale (see the Ballot_Pedia article for more on the initiative). Legalizing marijuana will not, by itself, turn around our catastrophic prison overcrowding. Relatively few people are in prison for marijuana possession or even sale. However it can achieve two objectives that will move us in the right direction on crime policy and prisons.
First, legalizing marijuana will prevent the needless stigmatization and alienation of thousands of young (and not so young) adults who are discovered by the police to be in possession of marijuana, which is one of the leading cause of arrests in the United States. This will actually unburden the police who are usually searching for weapons, from having to arrest people they discover marijuana on, or appear to be ignoring law violations. Many police-citizen encounters will have a happier ending. More importantly, many people will not accumulate misdemeanor offenses on their record that can lead them to prison later, and will avoid unnecessary criminalization.
Second, legalizing marijuana will deliver the largest possible blow to heinous drug cartels in Mexico for whom marijuana constitutes the second largest source of profits (and possibly the largest). As decades of experience have taught us, profit centered criminal networks are almost impossible to defeat using normal criminal sanctions (because they can successfully recruit new members to replace any incarcerated ones so long as the profits remain high). As Mexico's disastrous military war on drugs is demonstrating, extra-judicial deterrence does not work any better, and does lead to hundreds of collateral casualties. Without firing a single bullet, California voters can cut the Mexican cartels down to size, making it harder for them to corrupt the Mexican political system, simply by moving those profits from the crime world to the world of lawfully regulated business.
We should not be glib about the costs of marijuana legalization. Making it legal for California adults to buy and possess marijuana will almost certainly lead to more people using more of the drug. A recent paper from RAND by my colleague Rob MacCoun and others uses econometric techniques to try and estimate those effects and they suggest far from trivial increases (here it is, but it may require authorization to access). While it is true that most people who want marijuana can easily find it now (especially given California's medical marijuana regime), there are actually some people out there who will not use it on principal simply because it remains against the law. More importantly, the convenience and reliability of obtaining marijuana once it is legal will very likely increase use (even if the price does not go down, which RAND assumes but has not been true under the medical regime and could be prevented by correct tax policy).
Marijuana can be psychologically addictive. Its capacity to lift the user above the humdrum of life and let them see things differently (enabling the poetry function) can be hard to resist. For creative artists and writers it may be a wonderful tool, but for people facing depressing circumstances it may become a way to ignore circumstances that need to be changed instead.
But here is where the argument for legalization becomes most promising. The best way to prevent and remedy addiction, is through outreach, education, and counseling to the user community. The current state of illegality makes that harder in countless ways. Once legalized, local regulation could require marijuana stores to provide all of those services to their clients, and creative regulators could celebrate innovations and circulate best practices widely.
And this is precisely where marijuana legalization could do the most good. By demonstrating, through empirically tested regulations, that civil governance can remedy the negative consequences of recreational drug use, the legal marijuana regime could help wean us from our dependence on criminal law as a way to govern America.