WHEN ARE PEOPLE TOO HIGH TO DRIVE?

A cop pulls over a motorist who's driving like he's drunk, but the
officer suspects the driver may be high on marijuana. Unlike with
alcohol, there's no objective way for police to detect whether
somebody is impaired while driving under the influence of marijuana.
There's no breath test for THC, pot's active ingredient, and no 0.08
limit to drive like California law sets for alcohol in the blood.

Now, as Californians consider making the state the first in the
country to legalize the recreational use of marijuana, police
officials are concerned that Proposition 19 could put an extremely
difficult burden on police: How will they determine whether a driver
is too drugged to drive?

The blood alcohol concentration in one's breath pretty closely tracks
how much booze is in a person's blood. Not so for THC, which is
absorbed by the fat in a person's body and stays there for days or
weeks after the marijuana is consumed.

That's because pot isn't metabolized by the body the same way alcohol
is, said Steven Gust, an official at the National Institute on Drug
Abuse. So just having THC in your system doesn't mean you're too
intoxicated to drive.

That means officers base arrests only on observations, field sobriety
tests and, ultimately, their judgment. To improve that judgment, the
California Highway Patrol uses the Drug Recognition Expert program to
train police throughout the state. More than 1,200 current officers
have received the training and 55,000 arrests have been made using
the program's evaluation techniques since 1992.

While there is no simple roadside THC test being used in California,
police in Australia and parts of Europe have started using saliva
tests during stops. Those are likely years away from general use and
have raised some legal questions, Gust said.

But even if California police start using the saliva tests, the
problem of no legal standard for THC intoxication remains.

Having a legal THC limit, for driving or public intoxication, hasn't
been necessary because marijuana is illegal, said San Mateo Police
Chief Susan Manheimer, who also heads the California Police Chiefs Association.

"It's a lot of science and years of work (to set a limit). Who's to
say that any level is OK?" she asked.

The effect alcohol has on drivers has undergone decades of testing.
The thousands of deaths attributed to drunken driving each year also
pushed lawmakers and researchers to focus on coming up with a
standard as well as increasingly stringent ways to enforce it, officials said.

Currently, prosecutors who want to prove drugged driving need to show
the driver was under the influence and, as result, couldn't safely
operate a vehicle. Prosecutors also need a positive drug test.

California has taken a less hard-line approach than that of 15 other
states, including Arizona, Nevada and Utah, which have adopted the
stance that any detectable level of THC is illegal. Manheimer said
lack of a "per se" law, which makes illegal any detectable amount,
and the unavailability of a simple roadside test have made it
difficult to convict stoned drivers.

She predicted the situation will only get worse if voters pass
Proposition 19 in November.

But Joshua Dale, head of the California DUI Lawyers Association, had
this to say about Manheimer's concerns: "It's a bunch of hooey."

He said if an officer has made a valid arrest, the jury is good and
so is the prosecutor, getting a drugged driving conviction is no
easier or harder than in alcohol-related cases. If police want
another layer of proof, he said, they should videotape and audio
record stops for suspected driving under the influence. The evidence,
if shown to a jury, will be enough to get a conviction as long as the
person was impaired.

It's hard to say how big of a problem drugged driving already is in
California because the Department of Motor Vehicles doesn't track the
issue. But California arrested 214,800 drivers and convicted 162,000
of them of DUI, which includes drugs and alcohol, in 2008 -- the most
recent year available.

A 2007 National Highway Transportation Safety Administration study
does give an idea of drug use nationally among drivers. The survey
found 16.3 percent of nighttime weekend drivers tested positive for
drugs, including 8.6 percent who were using ?marijuana. The survey
also found cocaine in 3.9 percent and over-the-counter and
prescription drugs in 3.9 percent.

But Dale Gieringer, head of the California wing of the National
Organization for the Reform of Marijuana Laws, asks, "So what?"

He said marijuana use was twice what it is now in 1979 and there
wasn't an epidemic then of stoned drivers running over people or
smashing into each other.

"We've been there before," he said. "There is no difference. Just
enforce the law."