 | NORML News: Govt plans for Driver Drug Testing: Reefer madness on the road? |
 NORML NEWS SUMMER 2008. BY HARRY CORDING (Additional reporting by Chris Fowlie)
The government wants to introduce a new offense of driving under the influence of illegal
drugs. Is it necessary - or reefer madness in a fluoro vest? Does the government need
something else to arrest us for? And with cannabis the most popular illegal drug, the question
arises: is stoned driving dangerous?
The Land Transport Amendment Bill (No 4)
passed its first reading in October. It creates
a new offence of driving while impaired by
drugs, and police will be able to order drivers
to undergo roadside tests for impairment, such
as balancing on one leg, or estimating when 30
seconds have elapsed. A driver who fails the
test will have to provide a blood sample, and
if an illegal drug is detected in the sample, an
offence will have been committed.
Penalties will be the same as for drink
driving. A person taking prescription medicine
would have a defence under the new law, but
not if they had disobeyed instructions.
At present police can prosecute a driver who
is “incapable” of driving properly because
of drugs, a much higher threshold than
“impaired”.
Predictably, all parties in Parliament are
supporting the measure. However, the Greens
negotiated a very significant amendment
which means evidence gathered under the new
law can not be used to lay charges under the
Misuse of Drugs Act.
Another significant improvement from what
was first proposed is that the Government has
agreed to only test for THC, which is in the
blood only while a person is high, and not the
inactive metabolite THC-COOH, which can
linger in the body for up to three months.
Importantly, they will also set a level of THC that
correlates with impairment from drunk
driving, rather than a zero limit. A new study by an international working
group of drug-driving experts has concluded
that “using a zero limit for legal determination
of impairment by cannabis ... would classify
inaccurately many drivers as driving under the
influence of, and being impaired by, the use of
cannabis.” The researchers said a THC level
of 7-10ng/ml of blood would equate to the
same level of impairment as a Blood Alcohol
Concentration (BAC) of 0.05%. (The current
New Zealand BAC legal limit is 0.08 although
there is talk of reducing this to 0.05)
While it’s well established that alcohol
increases the risk of causing driving accidents,
evidence of marijuana’s guilt is much less
convincing. A lot of research has been done in
recent years about the effects of cannabis on
driving, including driving simulator studies,
on-road performance studies, crash culpability
studies, and reviews of existing evidence.
The results are fairly consistent: marijuana
has a measurable yet relatively mild effect
on psychomotor skills, and does not appear
to play a significant role in vehicle crashes,
particularly when compared to alcohol.
A 2002 review of studies involving 7934
drivers reported, “Crash culpability studies
have failed to demonstrate that drivers with
cannabinoids in the blood are significantly
more likely than drug-free drivers to be
culpable in road crashes.”
Drivers who have smoked marijuana tend
to be aware of their impairment and therefore
drive more cautiously - the opposite of drivers
affected by alcohol, who tend to take greater
risks. A single glass of wine - well under the legal
limit - will impair your driving more than
smoking a joint. And under certain conditions,
the way alcohol and cannabis combine to affect
driving behaviour suggests that someone who
has taken both may drive less recklessly than
a person who is only drunk.
These are the findings of a study by the UK’s
Transport Research Laboratory. Researchers
gave 15 volunteers cannabis, alcohol or both
before testing them on a driving simulator.
Cannabis significantly affected only tracking
ability. Volunteers found it more difficult to
hold a constant speed and follow the middle
of the road accurately while driving around a
figure 8 loop. Those who drank the equivalent
of a glass of wine fared worse than those
who smoked a joint. Those who were given
both alcohol and cannabis performed worse
still, reinforcing the idea that alcohol has
a cumulative effect when taken with other
drugs. But the study also found that drivers
on cannabis tended to be aware of their
intoxicated state, and drove more cautiously to
compensate. Drinking alcohol didn’t offset this
caution, raising the possibility that drivers who
are moderately drunk might be better off under
some conditions if they had also smoked.
A 1997 examination of motor vehicle injuries
by the University of Michigan Transportation
Research Institute (USA) concluded that
alcohol is “the major drug associated with
injury,” and found no evidence to support
the accusation that illicit drugs are a major
factor in accidents. An earlier analysis by the
US National Highway Transportation Safety
Administration of 1882 drivers killed in
vehicle accidents also determined that alcohol,
not pot, was the “dominant problem” in drug-related
accidents.
Professor Jack Maclean, director of the road
accident research unit at Adelaide University,
said “It has been impossible to prove marijuana
affects driving adversely. There is no doubt
marijuana affects performance but it may be
it affects it in a favourable way by reducing
risk-taking.” He said the lack of proof that marijuana was
detrimental to driving was not due to lack of
effort by researchers. “There are some quite
distinguished researchers who are going
through incredible contortions to try and prove
that marijuana has to be a problem.”
He could have been talking about Professor
David Fergusson of the Christchurch School
of Medicine. In contrast to a large body of
research conducted over many years, his latest
report concluded that “the risks of driving
under the influence of cannabis may be greater
than the risks of driving under the influence
of alcohol.”
The Prof seems trapped in a cycle of issuing
sensationalist press releases every time a new
funding round comes up. His conclusions
are so heavily laced with caveats, howevers,
maybes, qualifiers and equivocations as to
render them practically meaningless - but
they’re enough to generate a rash of alarmist nonsense from politicians and the media.
Fergusson’s research was part of the
Christchurch Health and Development Study,
which has tracked the lives of 1265 children
born in the Christchurch region in 1977. The
936 drivers in the group reported greater rates
of driving under the influence of cannabis
than driving under the influence of alcohol.
The paper concluded that “driving under the
influence of cannabis posed a greater risk to
driver and vehicle safety than drink driving
... analysis of rates of self-reported motor
vehicle collisions showed that driving under
the influence of cannabis was marginally
associated with increased risks of collision,
whereas driving under the influence of alcohol
was not.”
The report did not explain why alcohol
was not associated with increased risks of
collision. The reported rates of collisions were
nearly the same, but cannabis was said to be
a greater risk.
The report did acknowledge: “These
conclusions are subject to caveats. First, the
findings describe the conditions that applied
to a specific cohort studied in a specific
social context. The analysis has been based
on self-report, and the true rates of driving
under the influence and collisions may differ
from the rates reported. Third, the collisions
were largely minor, and for the most part
did not involve injury. Finally, the results of
the present study may be specific to that age
group.”
Fergusson notes that “there is very little
legal deterrent to driving under the influence
of cannabis”. It’s a gap the prohibitionists are
all too keen to fill, but the question remains:
does the evidence justify a new law to target
stoner drivers? We don’t think so.
For more information see US NORML's guide to driving and marijuana, and their excellent summary of the latest research
Note: NORML recommends not driving or
operating machinery while impaired. See
our Principles of Responsible Marijuana
Use and guide to sensible cannabis use
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