The same day a Mesa police officer and prosecutor joined forces to warn the public about the dangers of driving under the influence of marijuana, defense attorney Aaron Black was preparing a case for court.

Last year, Black’s client was driving on a Mesa street when “allegedly, he made a reckless or improper U-turn in front of a motorcycle,” Black said. 

“The motorcycle ran into him,” he added.

When Black’s client told an investigating police officer he smoked marijuana the day before, he was cited for driving under the influence.

When the motorcycle rider died, Black’s client was charged with manslaughter.

Recreational use of marijuana for adults in Arizona became legal this year.

This, as Black sees it, accelerated a trend of police officers sniffing out drivers under the influence of marijuana.

“What’s going on is there are tons and tons of marijuana DUIs,” he said. “Police are much more trained on it and they’re on the lookout for it.” 

If a police officer believes a driver is impaired, the officer can request a field sobriety test. After seeing how the driver walks a straight line, follows hand signals and responds to instructions requiring multi-tasking, the officer can demand a test to see if the driver has ingested potentially impairing substances.

If alcohol is suspected, a portable Breathalyzer can be used to measure blood alcohol content (BAC).

But if the officer suspects the driver has ingested marijuana, there is no fast, portable test; but the officer can demand a blood test.

And that is what exasperates attorneys like Black.

“Science says everyone at .08 (BAC) is impaired,” he said. “But with marijuana, there’s no cutoff for impairment. Studies are showing chronic users of marijuana may show no signs of impairment at all. Whereas a novice user may show more signs of impairment.”

Black complained that the prosecution of potential marijuana DUI’s “rely on police officers’ observations … The state has to prove they’re impaired — but there’s no science behind it. The science says people may be impaired or they may not be.”


Impaired panel

Though police officers and prosecutors often don’t view things the same way as defense attorneys do, they agree with one of Black’s points: Marijuana does not affect everyone the same way.

This was one of the educational points of a June 1 Impaired Driving Education Awareness (IDEA) panel that streamed on Mesa Channel 11 and the city’s Facebook page.

George Chwe, a Mesa police officer and state coordinator of the Drug Evaluation Classification Program for the Governor’s Office of Highway Safety, and Stacey Good, an assistant city prosecutor, talked about marijuana as an impairing substance and how it is unsafe to drive a motor vehicle while under the influence.

Good agreed with a point Black made:

“Marijuana’s going to affect every person differently,” she said, before discussing the contrast with marijuana and alcohol tests. 

“With marijuana, there are no set standards. With alcohol, the effects are (standard) across the board. We don’t have that with marijuana,” the prosecutor stressed.

Blood tests can show if Tetrahydrocannabinol (THC) – which causes the brain to feel “high” – is present.

But ….

“It’s really hard to prove scientifically what level of THC is going to be impairing … we’re trying to catch up with that,” Good said.

As Black noted, the prosecuting attorney said marijuana impairment is judged by “field sobriety tests and your conversation” with a police officer.

Chwe is one of the officers called on to judge a driver’s potential impairment.

“We ask the question, ‘When’s the last time you smoked marijuana?’ It’s not necessarily are you going to be arrested? It’s how you react to our field tests,” Chwe said

“It’s whether (marijuana is) affecting you at that given moment and whether you’re impaired.”

Chwe noted that tests for alcohol and marijuana impairment are the same.

“A police officer’s job is to observe impairment and document that … for the most part it’s not going to change, it’s still the same standard field sobriety test we’ve done for years. They’re just going to have to document what they’re seeing better,” Chwe said. 


Toke or drive – not both

Black said he feels police are generally doing the best they can, though he doesn’t buy the results.

“I think they’re doing their job in recognizing (possible impairment), but I don’t think their field sobriety test is indicative of somebody being impaired by the drug,” Black said.

The defense attorney noted that drivers can refuse to take a field sobriety test, but cautioned against refusing to take a blood test:

“You’re not required to give a blood sample – but if you refuse, they suspend your license for a year and get a warrant (for the test) anyway.”

Good stressed that “edibles” like cookies, brownies and gummies that are laced with marijuana can be extremely powerful, especially for the weed novice.

She cited a case where someone ignored directions to consume small portions and ate an entire marijuana cookie:

“They told me they were still feeling the affect three days later.”

Whether smoked or ingested, marijuana can remain in the body — and show up on tests — for days and sometimes weeks.

For that reason, Black advises “not to drive for a couple days” after using marijuana.

To him, it’s a simple this-or-that formula to prevent trouble with the law:

“If you’re going to smoke marijuana, don’t drive. It’s one or the other.” ′

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