Pubdate: Tue, 10 May 2016
Source: Washington Post (DC)
Copyright: 2016 The Washington Post Company
Contact:  http://www.washingtonpost.com/
Details: http://www.mapinc.org/media/491
Author: Ashley Halsey III

SETTING DUI LIMITS FOR MARIJUANA WON'T WORK, AAA RESEARCHERS FIND

There Is No Reliable Number That Can Predict Impairment, Study Says

There is a legal limit for drunk driving, but when it comes to 
marijuana, new research shows it may be impossible to say just how 
high is too high to drive.

There's no breathalyzer for pot, and researchers say blood tests are 
useless when it comes to telling whether someone who has been smoking 
is fit to drive.

The question matters now that four states have made it legal for any 
adult to smoke marijuana, and more than 20 others have approved its 
use for medical reasons. In Washington, one of the first states to 
approve recreational marijuana use, a study released this week found 
that 17 percent of drivers involved in fatal crashes two years after 
marijuana was legalized had THC, the component that creates the high, 
in their system.

At least 20 states have approved laws on marijuana use by drivers. A 
dozen of them have made any use of the drug by those behind the wheel 
illegal; six others have set a legal limit similar to the .08 alcohol 
level, with any driver testing above it subject to a DUI conviction.

A report by researchers at the AAA Foundation for Traffic Safety said 
there is no threshold that indicates when a marijuana smoker may be 
too impaired to drive.

"There is no reliable number that has any meaningful value in terms 
of predicting impairment," said Jake Nelson, AAA's director of 
traffic safety and advocacy.

The AAA Foundation recommends doing away with setting legal limits 
for THC. Instead, it says each police department should put a cadre 
of officers through 72 hours of training, followed by field testing, 
to be certified as drug recognition experts (DRE).

If an officer suspected marijuana use, a DRE could be called in to 
conduct an hour-long series of tests, and if they provide 
confirmation, a blood test would "It shifts the burden of evidence 
from the prosecution to the defense," Nelson said. "If you can prove 
that you weren't [using pot], you can avoid conviction, but if you 
can't beat this case, then you're going to jail."

Nelson says that since there is no threshold, some people who are not 
fit to drive will get off the hook if they are stopped or involved in a crash.

"People who are driving impaired are still going to crash," he said. 
But "if you have a blood concentration of THC below whatever stated 
threshold it is in your state, essentially the courts will presume 
sobriety. The odds of getting convicted of impaired driving, even if 
you're all over the road, are slim to none because of that number. 
And because we know from the research that the number is meaningless, 
that there's no research that supports any stated threshold, so to 
have those laws on the books is bad news."

The second report released by the AAA Foundation this week examines 
the effect of marijuana use in Washington state, where recreational 
use has been legal for more than three years.

The numbers in Washington are made soft by a number of variables. For 
example, drivers who died within two hours of a fatal crash were 
likely to be tested for drugs and alcohol, those who died later were 
less likely to be tested, and those who survived were unlikely to be 
tested. What's more, many drivers who tested positive for THC also 
had alcohol in their system, considered a more potent mix than simply 
using one of the two intoxicants.

Still, the report found that in 2013, 8 percent of drivers in fatal 
crashes tested positive for marijuana use. In 2014, the number more 
than doubled to 17 percent.

"Of all the fatal crashes in the state, the proportion that involved 
a driver that had recently consumed marijuana more than doubled in 
one year," Nelson said. "That doesn't say that people who had smoked 
marijuana and got behind the wheel were responsible for an increase 
in fatal crashes. It means that recent marijuana use is a growing 
contributing factor in traffic crashes that kill people."
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MAP posted-by: Jay Bergstrom