Marijuana Policy: Changes and Challenges

An Interview with Rob MacCoun, PhD, Stanford Law School

Rob MacCoun is a social psychologist and professor of law at Stanford University and a member of the Stanford Network on Addiction Policy (SNAP). He works at the intersection of public policy, law, and the behavioral sciences and studies such topics as illicit drug use, drug policy, citizens’ assessments of fairness in the courts, and bias in the use and interpretation of research evidence by scientists, journalists and citizens. In this interview, he discusses the status and implications of marijuana policy in the U.S.

You’ve been studying the evolution and impacts of marijuana policy for a long time. What changes are happening in the U.S., and what challenges are policy makers facing?

We are at a point where marijuana law is changing very rapidly, especially at the state level, after a long period with little variation. We already have 10 states that have legalized recreational marijuana and 33 states that have legalized medical marijuana, with more states exploring both options. The federal government still has not legalized either at the federal level, which is an important source of tension in the law.

So far, the states that have legalized marijuana have adopted very similar models. They all took the lead of Colorado, basing recreational marijuana on the liquor model of private vendors and retail sales as opposed to state stores, buyers’ clubs and other options. As a researcher, I would love to see a thousand flowers bloom, because that’s how we're going to learn about what works best.

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What unanticipated challenges have the states encountered in the legalization process?

Marijuana legalization at the state level has produced a bunch of surprises, especially for state legislators. They expected massive amounts of revenue, and while they are pulling in revenue, it's falling short of their expectations. That's because they unrealistically made projections based on prohibition prices, even though we were telling them, "Price is going to drop." And prices have dropped—along with revenues.

Another surprise is that the black market didn't just disappear the way people predicted. So, all the states that have legalized still have very robust black markets as well.

One final surprise is the way in which people ingest marijuana. We have vaping, dabs, and edibles—all these new forms which are changing the market a lot. Then there’s CBD (cannabidiol, a compound found in the cannabis flower) and the anecdotal claims about its purported medical benefits.

If you had just one message for policy makers about marijuana, what would you tell them?

Policy makers in 40 states are asking "Should we jump in?" I would say that you don't need to follow the model that's been adopted in Washington or Colorado

or California. There are other ways to change marijuana laws: simply legalize home cultivation, which, I think, is a very low-risk strategy. Or look at buyers’ clubs or state stores.

What do policy makers need to know about edibles?

Edibles have been with us for a long time. Today’s edibles—candy products, colas, tasty treats, all in brightly colored packaging—are more popular than expected and now account for a sizable minority of the market.

The problem with edibles is that these brightly colored packages are very attractive to children who find them around the house. To their credit, many states are now making them child proof. But, what's child proof for a four-year-old is not child proof for an eight-year-old. We're seeing kids turning up in the emergency rooms very stoned because they ate a package of gummy bears when one gummy bear was the intended adult dose.

What is the most sensible way to tax marijuana?

Again, there are options. Colorado and Washington, through ballot initiatives, use excise taxes. When you purchase the marijuana, some percentage of that dollar price is added on as a tax. That's very easy to administer, which is the principal benefit. But with pre-tax

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prices of marijuana plummeting, the tax revenues plummet as well. Not only does the state get less money, but some of the public-health benefits of the tax aimed at discouraging heavy consumption also diminish.

An alternative is to tax by weight. That creates incentives for buyers that don't make a lot of sense. Probably the best way to tax marijuana would be to index it by THC content. That does not prohibit high levels of marijuana potency but it does make the user, as the economists say, "internalize the externalities," which, in this case, include higher probable risks.

One of the ongoing debates is whether marijuana is harmful. What does the research tell us about that?

For years, I told my students that marijuana is less harmful than the government is telling you, but it's more harmful than you think it is. All psychoactive drugs come with risk, including marijuana. There's a real phenomenon of marijuana dependency. Simply operationalized, a lot of people wish they were using less marijuana than they are. Marijuana has acute effects on psychomotor function that people need to worry about, but it also has chronic effects. The one that we are most concerned about right now is whether there is a link between marijuana and

psychosis. It’s not something you can dismiss out of hand, because there's so much correlational evidence. The peak years of onset for schizophrenia are in the 20s and that's also the peak period of onset for cannabis.

The real question is "What is the nature of that correlation?" Is it that marijuana causes people to become psychotic? Is it that people who are psychotic use marijuana to self-medicate? Or does

marijuana just tip someone who's right at the margin, very susceptible, into psychosis. I think the last explanation is probably the one that I would bet on, but I don't think we know yet.

Do we know why people use cannabis in the first place? There are a lot of reasons why people use marijuana—for psychotherapeutic reasons, for spiritual reasons, to enhance

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creativity. If you actually look at the correlates, the best predictors of cannabis use involve peer use, so there's a heavy social dimension to it. I think there's no question that cannabis gives people fun and pleasure. But a lot of people are also using cannabis to deal with chronic pain and other medical conditions.

Much opposition to marijuana legalization has been based on concerns that marijuana is a gateway drug and leads to using more addictive substances. What does the research show?

Two sets of big research questions are still not resolved around the link between marijuana and other drugs. One is the so-called gateway mechanism. Does marijuana increase the probability of moving onto hard drugs? And the other is the question of whether marijuana substitutes for other drugs like alcohol, or compliments them. A new variation on that is "Does marijuana substitute for opioids as a form of pain reduction?" We know that there's a correlation between marijuana use and hard drug use. We know, chronologically, that almost everyone who uses hard drugs started with marijuana. Whether that's causal, and why it's causal, is still unresolved. And the “why” is interesting, because the American perception has always been, "If there's a gateway, it's

something happening in the brain; once you develop this taste for psychoactive experience, you want to escalate it." My European research is just correlational, but it suggests that people who've used marijuana in the Netherlands are less likely to move onto hard drugs than in other European countries. So, I think if there's a gateway, it's not necessarily something in the brain; it might be something in the marketplace, or something about who you associate with.

The substitution question is complicated; studies show mixed results. We've got correlational evidence that in states where people can use marijuana medically, there's less use of opioids, but we don't know if that’s a substitution. Are people using marijuana instead of opioids or is that behavior driven by other characteristics in those states?

Another issue that is often raised is the relationship between marijuana and crime. Does legalization affect crime?

There's not really a causal mechanism that links marijuana to crime. Marijuana use does not make people more aggressive. There's not a phenomenon of people committing income-generating crimes to pay for their marijuana habit, which is something we saw with cocaine and heroin. There is an interesting

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backdoor connection though: marijuana enforcement takes resources away that could be dedicated to other kinds of crime fighting. But that's a small mechanism.

What do you think is behind the current wave of decriminalization legalization—is it driven by public opinion or other factors?

We’ve seen a big change in public opinion in a relatively short period of time; people are more willing to admit favorable attitudes toward legalization than in the past. But that's not the whole story. I think what we're seeing involves different birth cohorts. If you really break down the public opinion data, you see that people who went to high school before the era in which marijuana was widely available tend to be very opposed to marijuana legalization, and those birth cohorts are getting older and are dying off.

Birth cohorts that grew up around marijuana are not necessarily enthusiasts of marijuana legalization, but they don't see it as a big deal. They just don't understand what all the fuss is about. As those younger birth cohorts become voters, they're willing to support change. And for that reason, I think the wind is really in the sails for legalization. ¤