As we all know, Colorado’s legalization of recreational marijuana went into effect the other day, and Washington will soon follow. I would spend some time discussing the merits of legalization, but I largely agree with Grover’s post on Green Wednesday. As one might expect, it didn’t take long for the op-eds to offer their opposition to legalization.

David Brooks (NYT) weighs in on the issue. He remembers his days smoking weed as an adolescent and assures us that he is no prude (“I don’t have any problem with somebody who gets high from time to time, but I guess, on the whole, I think being stoned is not a particularly uplifting form of pleasure and should be discouraged more than encouraged.”) The real concern is the impact of marijuana on the adolescent mind and the impact of legalization on marijuana use. Ruth Marcus (in WaPo) focuses on this issue, arguing that “our children will not be better off with another legal mind-altering substance.” If early marijuana use has negative impacts on the adolescent brain (Marcus cites research that “long-term users saw an average decline of eight IQ points”) this should be a source of concern. Of course, Colorado does not legalize the use of marijuana by people under age 21—a point that Marcus acknowledges—but this is beside the point. Alcohol is prohibited for those under 21, and yet illegal drinking is widespread. The core issue for Marcus: “although alcohol seems to be the teen drug of choice among the adolescents I know, the more widely available marijuana becomes, the more minors will use it.”

Brooks arrives at the same conclusion:

We now have a couple states — Colorado and Washington — that have gone into the business of effectively encouraging drug use. By making weed legal, they are creating a situation in which the price will drop substantially. One RAND study suggests that prices could plummet by up to 90 percent, before taxes and such. As prices drop and legal fears go away, usage is bound to increase. This is simple economics, and it is confirmed by much research. Colorado and Washington, in other words, are producing more users.

It is simple economics: legalization should result in a reduction in prices. A reduction in prices should lead adolescents who drink alcohol to consumer marijuana instead. The core question: is this necessarily a bad thing?

Let us agree for the sake of argument that the best state of affairs would be one in which adolescents did not desire intoxication (we can agree with Brooks that “being stoned is not a particularly uplifting form of pleasure.”) But assuming that there is (1) a universal desire for intoxication and (2) adolescents will violate the law, attention must focus on the question of substitution. If adolescents substitute marijuana for alcohol, this might not be as serious a problem as Brooks and Marcus suggest. Alcohol also impairs development of the adolescent mind. Problems of dependence are more significant for alcohol than they are for marijuana (but less significant than for cocaine, heroin, and nicotine). And although deaths from alcohol poisoning are commonplace, it is difficult to find evidence of anyone having died from an overdose of marijuana (as Robert Gale writes in American Scientist: “I’ve found no published cases in the English language that document deaths from smoked marijuana, so the actual lethal dose is a mystery.”)

Moreover, there is the iron law of prohibition. In essence, the more intense the prohibition, the more potent prohibited substances become. Marijuana prohibition creates incentives to develop more potent strains of marijuana (higher return relative to risk) and alternative drugs that are less easily interdicted but potentially more toxic. The prices for marijuana may increase, but the prices for more dangerous intoxicants (like heroin, crack cocaine and crystal meth) fall. One should not be surprised that when adjusted for purity and inflation, the retail price for opiates in 2007 was 22.6 percent what it had been in 1990; in 2008, the retail price for cocaine (adjusted once again for purity and inflation) was 51.5 percent what it had been in 1990 (Source: UN Office on Drugs and Crime).

In my mind, those who oppose legalization need to move beyond the objections presented by Brooks and Marcus. Assuming that some adolescents will pursue intoxication, it may well be the case that marijuana is the least-worst alternative. Rather, critics should confront the massive human and financial costs–and the unintended consequences–of the current war on drugs and ask a simple question: what would a rational drug policy look like? At the very least, it would create incentives for those seeking intoxication to use the least dangerous intoxicants. To the extent that legalization has this effect, it is arguably a movement in the right direction.