Pubdate: Tue, 05 Aug 2014
Source: Washington Post (DC)
Copyright: 2014 The Washington Post Company
Author: Radley Balko


Since Colorado voters legalized pot in 2012, prohibition supporters
have warned that recreational marijuana will lead to a scourge of 
"drugged divers" on the state's roads.

They often point out that when the state legalized medical marijuana
in 2001, there was a surge in drivers found to have smoked pot. They
also point to studies showing that in other states that have legalized
pot for medical purposes, we've seen an increase in the number of
drivers testing positive for the drug who were involved in fatal car

The anti-pot group SAM recently pointed out that even before the first
legal pot store opened in Washington state, the number of drivers in
that state testing positive for pot jumped by a third.

The problem with these criticisms is that we can test only for the
presence of marijuana metabolites, not for inebriation. Metabolites
can linger in the body for days after the drug's effects wear off -
sometimes even for weeks.

Because we all metabolize drugs differently (and at different times
and under different conditions), all that a positive test tells us is
that the driver has smoked pot at some point in the past few days or

It makes sense that loosening restrictions on pot would result in a
higher percentage of drivers involved in fatal traffic accidents
having smoked the drug at some point over the past few days or weeks.

You'd also expect to find that a higher percentage of churchgoers,
good Samaritans and soup kitchen volunteers would have pot in their
system. You'd expect a similar result among any large sampling of people.

This doesn't necessarily mean that marijuana caused or was even a
contributing factor to accidents, traffic violations or fatalities.

This isn't an argument that pot wasn't a factor in at least some of
those accidents, either.

But that's precisely the point.

A post-accident test for marijuana metabolites doesn't tell us much at
all about whether pot contributed to the accident.

Since the new Colorado law took effect in January, the "drugged
driver" panic has only intensified. I've already written about one
dubious example, in which the Colorado Highway Patrol and some local
and national media perpetuated a story that a driver was high on pot
when he slammed into a couple of police cars parked on an interstate
exit ramp. While the driver did have some pot in his system, his
blood-alcohol level was off the charts and was far more likely the
cause of the accident. In my colleague Marc Fisher's recent dispatch
from Colorado, law enforcement officials there and in bordering states
warned that they're seeing more drugged drivers.

Congress recently held hearings on the matter, complete with dire
predictions such as "We are going to have a lot more people stoned on
the highway and there will be consequences," from Rep. John Mica
(R-Fla.). Some have called for a zero tolerance policy - if you're
driving with any trace of pot in your system, you're guilty of a DWI.
That would effectively ban anyone who smokes pot from driving for up
to a couple of weeks after their last joint, including people who
legitimately use the drug for medical reasons.

It seems to me that the best way to gauge the effect legalization has
had on the roadways is to look at what has happened on the roads since
legalization took effect.

Here's a month-by-month comparison of highway fatalities in Colorado
through the first seven months of this year and last year. For a more
thorough comparison, I've also included the highest fatality figures
for each month since 2002, the lowest for each month since 2002 and
the average for each month since 2002.

As you can see, roadway fatalities this year are down from last year,
and down from the 13-year average.

Of the seven months so far this year, five months saw a lower fatality
figure this year than last, two months saw a slightly higher figure
this year, and in one month the two figures were equal.

If we add up the total fatalities from January through July, it looks
like this:

Here, the "high" bar (pardon the pun) is what you get when you add the
worst January since 2002 to the worst February, to the worst March,
and so on. The "low" bar is the sum total of the safest January,
February, etc., since 2002. What's notable here is that the totals so
far in 2014 are closer to the safest composite year since 2002 than to
the average year since 2002. I should also add here that these are
total fatalities. If we were to calculate these figures as a rate -
say, miles driven per fatality - the drop would be starker, both for
this year and since Colorado legalized medical marijuana in 2001.
While the number of miles Americans drive annually has leveled off
nationally since the mid-2000s, the number of total miles traveled
continues to go up in Colorado. If we were to measure by rate, then,
the state would be at lows unseen in decades.

The figures are similar in states that have legalized medical
marijuana. While some studies have shown that the number of drivers
involved in fatal collisions who test positive for marijuana has
steadily increased as pot has become more available, other studies
have shown that overall traffic fatalities in those states have dropped.

Again, because the pot tests only measure for recent pot use, not
inebriation, there's nothing inconsistent about those results.

Of course, the continuing drop in roadway fatalities, in Colorado and
elsewhere, is due to a variety of factors, such as better-built cars
and trucks, improved safety features and better road engineering.
These figures in and of themselves only indicate that the roads are
getting safer; they don't suggest that pot had anything to do with it.
We're also only seven months in. Maybe these figures will change.

Finally, it's also possible that if it weren't for legal pot, the 2014
figures would be even lower.

There's no real way to know that. We can only look at the data

But you can bet that if fatalities were up this year, prohibition
supporters would be blaming it on legal marijuana. (Interestingly,
though road fatalities have generally been falling in Colorado for a
long time, 2013 actually saw a slight increase from 2012. So
fatalities are down the year after legalization, after having gone up
the year before.)

That said, some researchers have gone so far as to suggest that better
access to pot is making the roads safer, at least marginally. The
theory is that people are substituting pot for alcohol, and pot causes
less driver impairment than booze.

I'd need to see more studies before I'd be ready to endorse that

For example, there's also some research contradicting the theory that
drinkers are ready to substitute pot for alcohol.

But the data are far more supportive of that than of the claims that
stoned drivers are menacing Colorado's roadways.

CLARIFICATION: I wrote that "we can test only for the presence of
marijuana metabolites, not for inebriation." That isn't quite
accurate. This is true of roadside tests.

But a blood test taken at a hospitals can measure for THC, the
psychoactive ingredient in marijuana.

That said, even here there are problems.

Regular users can have still have remnant THC in their blood well
after the effects have worn off. Regular users can also have levels
above the legal limit and still drive perfectly well. In Colorado, a
THC level of 5 nano grams or more brings a presumptive charge of
driving under the influence.

However, references to "marijuana-related" accidents in studies, by
prohibitionists, and by law enforcement could refer to any measure or
trace of the drug. So when officials and legalization opponents talk
about increases in these figures, it still isn't clear what any of
this means for road safety.

Radley Balko blogs about criminal justice, the drug war and civil
liberties for The Washington Post. He is the author of the book "Rise of
the Warrior Cop: The Militarization of America's Police Forces."
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