Policy Perspective: A Conversation with Andrea Roth
Andrea Roth serves as Assistant Professor at the University of California, Berkeley
School of Law. She is the author of “The Uneasy Case for Marijuana as Chemical Impairment
Under a Science-Based Jurisprudence of Dangerousness,” a 70-page article which is
forthcoming in the California Law Review but already available online. Her article
studies the history of DUI in the case of alcohol, and compares the science and policy
issues of alcohol with those involving marijuana.
In my capacity as a Steering Committee member of the Blue Ribbon Commission on
Marijuana Policy, I was interested in speaking with Andrea to learn about this important
dimension of public policy. This is one of many conversations I am having and will be
sharing as part of the Policy Perspectives Series of the Blue Ribbon Commission.
- Abdi Soltani, Steering Committee Member, Blue Ribbon Commission 4/20/15
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ABDI: You have written an article that is getting a lot of praise from people who have
read it. I hope many people read it. But let me start by asking how did you develop
your interest in issues related to driving under the influence? I mean, how does a law
professor decide, I am going to focus on DUI?
ANDREA: I came to the world of DUI by way of being interested in how the age of
machines have transformed criminal justice. DUI is, in some ways, the ultimate trial by
machine. First, a machine measures the alcohol in the breath. We had the Drunkometer
in the 30s, now we have the Intoxilyzer. Second, we now define the very crime of drunk
driving in terms of a machine result. All 50 states have passed per se DUI laws that
criminalize driving with a blood alcohol level of .08 percent. That type of mechanical
liability in criminal law is interesting to me.
ABDI: How did the current system for determining alcohol in the human body for the
purposes of roads come about? What would you want people to know about that
history? Do you feel it was based more on science, politics, or on just practical issues?
ANDREA: I think the public should be aware that the .08 standard is based on decades
of careful scientific research – specifically single-car crash and case-control studies – on
how specific blood alcohol concentration increases relative crash risk. Based on such
studies, there is a predictable, linear relationship between blood alcohol level and crash
risk. And crash risk, as a sign of morally blameworthy dangerousness, has always been
what we look to in deciding how to criminalize chemical impairment from a drug that is
not illegal. Attempts to lower the level to .05 failed because the increase in risk at .05 is
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not significant enough in the minds of the public to justify criminal punishment. The
reason zero-tolerance laws work for DUI cocaine is that possession of the drug itself is
morally blameworthy, so driving with any amount of the drug in your body is morally
blameworthy. That logic doesn’t work with alcohol or legal marijuana – you have to
look to dangerousness, as measured by crash risk.
ABDI: What about alcohol makes it predictable?
ANDREA: The process by which ethyl alcohol affects the mind and acts upon the body
is similar in everyone. It is an unusually simple drug that makes alcohol-related crash
risk relatively easy to study. When we drink a glass of wine, the alcohol travels quickly
and evenly to the blood and the brain. It is both water and fat soluble and is only potent
in high enough amounts to ensure broad distribution through the body. If you have a
certain blood alcohol level, you also have a certain level of brain intoxication. Alcohol
leaves the body quickly and efficiently so your blood alcohol level doesn’t stay high for
hours after you drink.
ABDI: How is marijuana the same and how is marijuana different than alcohol, just at
the biological level in the human body?
ANDREA: Marijuana is the same in the sense that we know it causes intoxication just
like alcohol and so many other drugs. But it is different in three key respects.
First, there is no linear relationship between the level of THC in the blood and the level
of intoxication in the brain. When you smoke marijuana, more than 2000 compounds are
broken down. THC is the most psychoactive but it is not water soluble and doesn’t
uniformly affect the blood and brain.
Second, unlike alcohol, THC can stay in one’s system for hours or days after ingestion
and its metabolites can stay for days or weeks in an unpredictable fashion.
And third, scientists don’t agree on precisely how or why THC affects the brain. Its
efficiency and potency depend on a number of factors, like mode of ingestion, dosage
and history of the user.
ABDI: Given what you have learned, what should people know about how you can
approach DUI issues for marijuana?
ANDREA: First, we can’t legitimately create a criminal per se DUI marijuana law and
claim it is analogous to .08 unless we establish a relationship between level of a chemical
like THC and increased relative crash risk through scientifically valid studies. The
single-car crash and case-control studies that have been done where drivers have been
tested for marijuana show no such relationship based on THC blood levels. And while
multiple-car crash studies are harder to draw inferences from, those too suggest no such
relationship. The National Highway Transportation and Safety Administration just
published a case-control study in February 2015 finding no increased relative crash risk
related to THC alone. By criminalizing DUI marijuana based on THC blood levels absent
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any relationship to increased relative crash risk, we label and punish as criminals people
who have not been demonstrated to be at a morally blameworthy level of chemical
impairment. Anecdotes abound of chronic medical marijuana users who wake up with a
high THC blood level but are not impaired at all. We need to insist upon research rather
than settling for sloppy and irresponsible analogies to .08 that are not backed up by
science.
ABDI: Would you get in a car or put your kids into a car with someone who had been
smoking marijuana?
ANDREA: Probably not, just as I might not put them in a car with someone who was a
new or aggressive driver or who had been drinking at all. But my caution as a mother is
not the standard for moral blameworthiness leading to criminal punishment based on
chemical impairment. If we want to discourage behaviors we find risky, even if they are
not morally blameworthy, such as driving a little too fast or not wearing your seatbelt,
the way to do that is through the regulatory state, not criminal law.
ABDI: If you were talking to a chief of police, who is looking at the practical issue of
how to deploy their officers to keeps roads safe, what would you want them to know
and think about?
ANDREA: I’d want them to seek more funding to train officers as drug recognition
experts (DREs), to give prosecutors better tools to secure convictions without relying on
arbitrary numbers. I’d suggest deploying cameras to document drug induced
impairment to corroborate police officer testimony. I’d want them to seek grants to get a
breath or saliva or hair test that might have a shorter window of detection than a blood
test and would allow quicker sampling. A police officer invented the Breathalyzer and a
police-consultant chemist invented the Drunkometer. Perhaps a law enforcement officer
might invent an oral fluid test for THC that shows a meaningful relationship between
oral levels and crash risk. We won’t know until we try.
ABDI: And if you were talking to a policymaker, who is trying to figure out a state
system of marijuana regulation as it relates to DUI, what’s the main thing you want
them to be thinking about?
ANDREA: When policymakers think about criminalizing chemical impairment in
drivers, they need to base such a law on one of two legitimate penal theories. One is a
jurisprudence of prohibition, where possession of the substance is morally blameworthy
so driving with any amount is too. The second is a jurisprudence of dangerousness,
where you criminalize a certain level of chemical impairment demonstrably associated
with a morally blameworthy level of risk – here, relative risk of a car crash. The level of
dangerousness doesn’t depend on whether the drug is legal. To justify a per se THCblood-level DUI marijuana on a dangerousness theory, you would have to scientifically
establish the existence of a predictable linear relationship between THC blood levels and
increased relative crash risk. That science does not exist. In the meantime, policymakers
could still use administrative law to regulate marijuana and driving, just like they
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regulate speeding. And they could give police cameras and DRE training to better secure
convictions in DUI marijuana cases under existing subjective impairment laws.
ABDI: Is there anything else you want people to know and think about?
ANDREA: I would want people to recognize that we can still combat drugged driving
without relying on morally incoherent numerical standards, and to think critically about
any claim made in the heat of political battles that marijuana legalization will lead to a
“drugged driving” crisis. An Arizona Department of Public Safety review in 2012 found
that less than 1 percent of suspected impaired drivers for an entire year involved in
crashes leading to injury or death tested positive only for THC. Compare that to the
latest roadside surveys suggesting that 7 percent of drivers test positive for THC. If there
is a drugged driving crisis, it doesn’t seem to involve people with only THC, and no
other drug, in their blood.
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