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September 5, 2011

Recognizing a tough reality for marijuana legalization advocates

I have in the past asked what is the best argument supporting broad and serious prohibitions on marijuana use (see this post), and I have come around to the view that it finds indirect expression in this Denver Post article headlined "Driving while stoned difficult to define, regulate in Colorado."  Here are excerpts:

The number of drivers caught behind the wheel after using marijuana this year in Colorado is on pace to eclipse last year's total, adding fuel to cannabis critics' fears that the state is facing a growing problem of stoned driving.

But it is deeply in doubt whether the legislature next year will reconsider one proposal addressing the issue: creating a measurement by which drivers would be presumed too stoned to drive, which would make it easier for prosecutors to punish those who take the wheel while high....

The ultimate decision of whether to re-introduce a bill creating a "per se" limit of the amount of active THC drivers could have in their systems is still a ways off.  THC is marijuana's psychoactive chemical.  On Wednesday, a study group will present its research to a subcommittee of the state's Commission on Criminal and Juvenile Justice.... Significantly, the study group split sharply over whether a limit is appropriate. "There was considerable doubt whether there is enough science to set a per se limit for all people," said Sean McAllister, a medical-marijuana attorney who is part of the study group and who doesn't support a limit at this time.

Figures on motorists suspected of driving stoned hint at the debate.  Last year, the state health department lab screened nearly 2,600 blood samples for THC, with about 1,600 of those coming back positive.  Of the positive samples, about 500 had levels higher than 5 nanograms of THC per milliliter of blood — the amount that lawmakers earlier this year proposed as the per se limit. So far this year, the state has tested more than 2,200 samples, with about 1,000 positives and another 360 presumed positive but awaiting the required second confirmation.  About 250 have registered above 5 ng/ml.

Meanwhile, medical-marijuana advocates like McAllister say some research suggests certain drivers who test above 5 ng/ml can still qualify as sober.  And McAllister questioned the need for a per se limit — which eases the burden on prosecutors to prove impairment.  He said prosecutors already have roughly a 90 percent success rate winning convictions when stoned-driving cases go to trial.   "The science doesn't seem finished yet on the issue of DUI and marijuana," McAllister said.

Other statistics cloud the issue.  In 2010, 32 drivers who tested positive for marijuana were involved in fatal accidents, according to the Colorado Department of Transportation — though it is unknown whether those drivers were at fault in the accident or were stoned enough to be impaired.  In 2009, when fewer drivers total tested positive for pot, 37 drivers in fatal accidents were THC-positive. In 2008, the number was 31.

Arapahoe County Sheriff Grayson Robinson, who is also part of the study group, said he believes marijuana-impaired drivers are a serious danger and that a limit is needed.  But he said the details of such a limit are difficult to agree upon. "The difficulties we're having," he said, "are the nuances."

I do not see merely the fact that some people drive stoned and even have serious car accidents while stoned to be a strong argument against marijuana legalization.  After all, (many more) people get in accidents driving drunk or while texting, but that fact alone hardly support a climinal ban on all alcohol or smart phones.  But, as this article suggests, pro-marijuana advocates are likely to be vocal and persistent advocates against any stringent marijuana regulations, which I fear risks turning off moderate voters who are not morally against marijuana legalization but are pragmatically concerned about its potential consequences.  (And this debate is taking place in Colorado which, as detailed here, may have a pot legaltization initiative on the ballot in 2012.)

If pot prohibition supporters can showcase persistent resistance to what seems like reasonable "stoned driving" proposals and other similar regulations, it undercuts common claims that we could readily control legal marijuana's benefits and harms like we control alcohol's.  Though this not really an argument supporting pot prohibition, my point is that these kinds of stories give more heft to the slippery-slope-type concerns that pot prohibition supporters often bring up in these discussions.

Some older and newer related posts on pot policy and politics:

September 5, 2011 at 02:08 PM | Permalink


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Drunk driving is a big money generator for government.

Here is a suggestion from the real world about marijuana and driving.

Wait until a crash or other damage takes place, investigate it. If marijuana intoxication was a factor, then press impaired driving charges. That would make any marijuana intake before driving a genuine malum in se, rather than an arbitrary and false malum prohibitum with uncertain effect of any blood level.

THC has a long half life and accumulates in fat. That is why experienced users get high quickly. This effect contrasts with the short acting alcohol. It has less effect on experienced users than on non-users (habituation). In Australia, over 20% of murder victims had THC, and 10% of suicides. This is still less than alcohol found in half of those groups.

Either enforce prohibition of alcohol with extreme punishment, or legalize marijuana. The current situation is not logical. The legalization of marijuana would result in more crashes, suicides and murders. However, the benefits from legalization are so enormous that those side effects are likely worth it. Bringing in the income from this crop would grow the economy, not to mention our freedom. Most people can drink socially. The same is true for smoking marijuana.

Posted by: Supremacy Claus | Sep 5, 2011 3:16:19 PM

The main difficulty in establishing a blood THC level is that its half-life is very long; thus THC blood levels won't reliably equate with present intoxication. Of course, in many jurisdictions, a DWI conviction doesn't require a breath or blood test - simple testimony from an police officer is sufficient.

Posted by: SteveErickson | Sep 5, 2011 6:33:37 PM

All of these issues--whether marijuana use impairs driving ability, whether marijuana use has caused accidents, and even to some extent what level of THC in the blood indicates actual impairment--can be resolved with some degree of certainty quite easily. We can determine whether the numbers of people involved in accidents, who have THC in their blood, is statistically significant by applying the usual statistical methods. We can give people marijuana and run them through driving tests to determine whether they are unable to drive. We can do all sorts of tests to figure these things out.

But none of the answers would tell us whether we should legalize marijuana.

Posted by: Anonymous | Sep 5, 2011 9:56:58 PM

Just to put it in perspective, there were 158 alcohol related fatalities in CO in 2009.

Posted by: dm | Sep 5, 2011 11:42:44 PM

@Supremacy Claus:

Your assertion that marijuana legalization would result in more crashes, suicides, and murders is contradicted by all available evidence.

As you are undoubtedly aware, a number of states, starting with California, have legalized marijuana for medical purposes. In practice, marijuana has been legalized for any adult willing to spend $100 to obtain a physician's recommendation.

Let's have a look at the results in California:

Murder rate per 100,000 population
1996: 9.1
2009: 5.3
Source: http://www.ucrdatatool.gov/Search/Crime/State/RunCrimeStatebyState.cfm

Motor vehicle fatality rate (per 100 million vehicle miles traveled)
1996: 1.43
2008: 1.05
Source: http://www-fars.nhtsa.dot.gov/States/StatesFatalitiesFatalityRates.aspx

I'll confess that I don't know where to find the relevant statistics on California suicide rates, but given the lack of news on a surge therein, it's safe to assume that Proposition 215 didn't lead Californians to start offing themselves in significantly greater numbers.

If marijuana legalization were indeed going to result in any negative social consequences, these would have already manifested themselves in states which have partially legalized marijuana through medical allowance statutes. The fact that public health and safety have been unaffected by medical mj laws, indicates that they are unlikely to be negatively affected by full legalization.

(I am a full-time businessman and part-time marijuana legalization advocate.)

Posted by: pfroehlich2004 | Sep 6, 2011 2:56:59 AM

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