Regarding the Marijuana Policy Project report on laws and teen use

I briefly mentioned the MPP report on Monday (Laws don’t curb teen marijuana use), and I wanted to point out a couple of less-than-stellar reviews that it got from drug policy reform fans.

• Jacob Sullum has a thoughtful analysis at Reason
• The Drug Law Blog takes me to task for being inaccurate with my characterization of the report, and does a fine job of criticizing the report for its reliance on big-picture rather than specific statistical support.

Thing is, I agree with both of them and yet still stand by my approval of the MPP report.
How can this be, you ask?
Here’s my thinking.
First, there’s no real way to definitively answer the question as to whether laws reduce or increase or have no affect on marijuana and teens, for a number of reasons.

1. It’s an impossible question, given that a myriad of factors can be involved, including trends, fads, effects of education, substitution factors, etc.
2. Reporting data is extremely unreliable. Survey results when getting people to self-report illegal behavior are prone to intentional error (in both ways).
3. The definitions are ineffective — since the government allows no difference in the definition of use and abuse, someone who uses occasionally with no ill effects (the equivalent of wine with a dinner) is treated the same statistically as a heavy or problem user).
4. No laboratories. The federal government has, through international treaty, and interference with state initiatives, actively worked to stop any attempt at a current day laboratory situation in a country or state to have a situation where we could legitimately compare the effects of marijuana laws versus marijuana regulation only.

The fact that there is no way to definitively answer the question has not prevented the government from doing so — at every opportunity, and largely unchallenged. And its answer has been that drug laws reduce marijuana use. Period. That has become the de-facto assumption that everyone operates under, despite the fact that the onus of proof should be on the government, and they have been unable to prove it. Sure, they trot out meaningless micro-statistics (like “Marijuana use from 2002-2004 went down 4% by teens aged 15-17 — a clear indication that the drug laws are working” [note: don’t check that figure, I just made that one up]) And so every time the Drug Czar puts out one of those figures, the press eats it up and dutifully reports that the drug war is working.
It is in this context that the MPP report must be viewed. On its own, it has minimal statistical value or confidence. However, it was never intended to be viewed as a stand-alone item. Note the press release when MPP issued the report on Monday:

A new report from the Marijuana Policy Project (MPP) in Washington, D.C., challenges the key assumption underlying present U.S. marijuana laws: that marijuana must be prohibited for adults in order to deter teens from using it.
MPP’s report, available at www.mpp.org/teenuse, comes as the federal government prepares to release its annual “Monitoring the Future” survey of teenage drug use, which is traditionally released in mid-December. [emphasis added]

It’s clear that the purpose of the MPP report is to provide context to the federal government’s misuse of data.
We cannot continue to allow the government to establish the factual base when it is, in fact, not factual. One thing that we can do is convince the press to question the underlying assumption. I believe that was the purpose of this report, and it works.
No, MPP did not come out with any startling new information, or clear data results that say “Look! Marijuana laws cause marijuana use!” nor did they specifically represent it in that way. Sure, they were perhaps a little over-confident in their interpretation (though not even close to what comes from the federal government [no excuse, I know]), but again the way this report is to be used is primarily to force the press to question, and it’s particularly aimed at the press who don’t otherwise know enough to question the government’s contentions.
Now, when a member of the media prints the regurgitated data from the ONDCP, they have the ability to add “although critics contend that drug laws have limited effect on teen marijuana use, and may even have a reverse effect in some situations.”
This report isn’t for Jacob Sullum — he knows a lot more by himself than is revealed in the report. It’s for the reporter who has only a peripheral view of drug policy and assumes that what the government puts out must be true.
One additional note: On the “Gateway” effect. Drug Law Blog notes:

I’m also kind of amazed that the MPP in this study invokes the so-called “gateway effect” of marijuana when, in other contexts, I’m quite sure that they would deny (reasonably) that the use of marijuana is necessarily a gateway to harder drugs.

MPP in this situation invokes the gateway effect of black-market prohibition, which is different than the gateway effect of marijuana. The marijuana gateway effect says that marijuana use leads to other drugs. The black-market prohibition gateway effect says that the prohibition of marijuana puts people who use marijuana in greater proximity with other drugs since they have to buy it on the black market. There is absolutely no evidence for the marijuana gateway effect — if there is a gateway effect at all (uncertain), it’s more likely to exist as a black-market prohibition gateway.
Of course, the word “gateway” is a problematic one, since its definition has become so muddy. Some assume that it means “causal condition” while others use it to simply refer to an “anecdotal sequence.”