Pubdate: Tue, 10 May 2016
Source: Garden Island (Lihue, HI)
Copyright: 2016 Associated Press
Author: Joan Lowy, Associated Press


Study: No Scientific Basis for Laws on Marijuana and Driving

WASHINGTON (AP) - Six states that allow marijuana use legal tests to 
determine driving while impaired by the drug that have no scientific 
basis, according to a study by the nation's largest automobile club 
that calls for scrapping those laws.

The study commissioned by AAA's safety foundation said it's not 
possible to set a blood-test threshold for THC, the chemical in 
marijuana that makes people high, that can reliably determine 
impairment. Yet the laws in five of the six states automatically 
presume a driver guilty if that person tests higher than the limit, 
and not guilty if it's lower.

As a result, drivers who are unsafe may be going free while others 
may be wrongly convicted, the foundation said.

The foundation recommends replacing the laws with ones that rely on 
specially trained police officers to determine if a driver is 
impaired, backed up by a test for the presence of THC rather than a 
specific threshold. The officers are supposed to screen for dozens of 
indicators of drug use, from pupil dilation and tongue color to behavior.

The foundation's recommendation to scrap the laws in Colorado, 
Montana, Nevada, Ohio, Pennsylvania and Washington comes as 
legislatures in several more states consider adopting similar laws.

At least three states, and possibly as many as eleven, will vote this 
fall on ballot measures to legalize marijuana for either recreational 
or medicinal use, or both. Several legislatures are also considering 
legalization bills.

"There is understandably a strong desire by both lawmakers and the 
public to create legal limits for marijuana impairment in the same 
manner we do alcohol," said Marshall Doney, AAA's president and CEO. 
"In the case of marijuana, this approach is flawed and not supported 
by scientific research."

Determining whether someone is impaired by marijuana, as opposed to 
having simply used the drug at some time, is far more complex than 
the simple and reliable tests that have been developed for alcohol impairment.

There's no science that shows drivers become impaired at a specific 
level of THC in the blood. A lot depends upon the individual. Drivers 
with relatively high levels of THC in their systems might not be 
impaired, especially if they are regular users, while others with 
relatively low levels may be unsafe behind the wheel.

Some drivers may be impaired when they are stopped by police, but by 
the time their blood is tested they have fallen below the legal 
threshold because active THC dissipates rapidly. The average time to 
collect blood from a suspected driver is often more than two hours 
because taking a blood sample typically requires a warrant and 
transport to a police station or hospital, the foundation said.

In addition, frequent users of the drug can exhibit persistent levels 
of the drug long after use, while THC levels can decline more rapidly 
among occasional users. Nine states, including some that have 
legalized marijuana for medicinal use, have zero-tolerance laws for 
driving and marijuana that make not only the presence of THC in a 
driver's blood illegal, but also the presence of its metabolites, 
which can linger for weeks after use.

That makes no sense, said Mark A. R. Kleiman, a New York University 
professor specializing in issues involving drugs and criminal policy. 
"A law against driving with THC in your bloodstream is not a law you 
can know you are obeying except by never smoking marijuana or never 
driving," he said.

He said rather than switching to a new kind of law as AAA recommends, 
states should consider simply making it a traffic violation.

Studies show that using marijuana and driving roughly doubles the 
risk of a crash, Kleiman said. By comparison, talking on a handsfree 
cellphone while driving - legal in all states - quadruples crash 
risk, he said. A blood alcohol content of .12, which is about the 
median amount in drunken driving cases, increases crash risk by about 
15 times, he said.

Driving with "a noisy child in the back of the car" is about as 
dangerous as using marijuana and driving, Kleiman said.

The exception is when a driver has both been using marijuana and 
drinking alcohol because the two substances together greatly heighten 
impairment, he said.

The foundation also released a second study that found the share of 
drivers in fatal crashes who had recently used marijuana doubled in 
Washington after the state legalized it for recreational use in December 2012.

 From 2013 to 2014, the share of drivers who had recently used 
marijuana rose from 8 percent to 17 percent.

While it stopped short of blaming the crashes on that increase, AAA 
traffic safety director Jake Nelson said traffic fatalities went up 6 
percent in Washington during that same while the fatalities nationally declined.
- ---
MAP posted-by: Jay Bergstrom