Category Archives: Drugged Driving

How Much Marijuana Does It Take to Impair Driving?

A number of posts on this blog have addressed the problems encountered in trying to measure levels of marijuana — or, more accurately the active ingredient Tetrahydrocannabinol ("THC") — in the blood of a person when he was driving.  See, for example, Oregon Legislative Study Criticizes "Per Se" DUI Marijuana Laws and Marijuana Legalization and the California DUI.   

More importantly, these and other posts have also raised the related but unanswered question:  How much marijuana in the human body does it take to render a driver unable to safely operate a motor vehicle in the manner of a sober person (the rough definition of "driving under the influence" or "driving while intoxicated")?  See New Efforts to Push Roadside Marijuana DUI Test

The following excerpts from a recent article in The Atlantic, entitled "When Are You Too Stoned To Drive?", provide an excellent analysis of these important issues: 


…We take for granted that not being able to walk a straight line or stand on one leg means that you’re drunk, and that being drunk means it’s unacceptably dangerous to drive. But there is no clear scientific consensus when it comes to smoking pot and driving. And few of the tools police officers have long relied on to determine whether a driver is too drunk to drive, like a breathalyzer, exist for marijuana…

Most (but not all) studies find that using pot impairs one’s ability to drive. However, overall, the impairment appears to be modest—akin to driving with a blood alcohol level of between .01 and .05, which is legal in all states. (The much greater risk is in combining pot with alcohol.) The increased crash risk with pot alone “is so small you can compare it to driving in darkness compared to driving in daylight,” says University of Oslo political scientist Rune Elvik, who conducted several major meta-analyses evaluating the risk of drugged driving…

When it comes to alcohol, science and the courts have long established a direct line between number of drinks, blood alcohol level, and crash risk. As one goes up, so do the others. Not so for pot. Scientists can’t say with confidence how much pot, in what concentration, used in what period of time, will reliably make someone “high.”…

Blood levels of THC—tetrahydrocannabinol, the chemical component of pot that makes you high—spike quickly after smoking and then decline rapidly in the hours afterwards, during the window when a smoker would feel most high. What’s more, regular smokers could have THC in their blood for days or weeks after smoking, when they are clearly no longer high.

Still, laws in 18 states tie drugged driving charges to whether drivers have THC (or related compounds) in their blood. Some states prohibit driving with any amount, and some specify a threshold modeled after the .08 limit states use for blood alcohol. But the lag time between being pulled over and being transported to a hospital for a blood draw—on average, more than two hours—can lead to false negatives, while the tolerance developed by regular users (and the tendency for THC to stick around in their bloodstreams) can lead to false positives. This is why, researchers say, blood THC laws make little sense… 


Scientific facts, however, have never prevented politicians from passing expedient and politically-popular laws, or police and prosecutors from enforcing them. 
 

Oregon Legislative Study Criticizes “Per Se” DUI Marijuana Laws

As I’ve posted often in the recent past, with the increasing use — and legalization — of marijuana, legislators and law enforcement are falling over themselves trying to come up with answers to many uncomfortable questions, such as:


Does marijuana, in fact, impair driving ability?

How does an officer detect recent use of marijuana in the field? 

How do you measure the amount of active marijuana (THC) in the body at the time of driving?

At what level of active ingredients in the body is a person impaired? 

How long do measurable amounts of marijuana stay in the body?

If impairment levels cannot be determined, is there an illegal per se level that can be used, such as .08% with alcohol? 


And as I’ve posted in the past, there are no accepted satisfactory answers to these and related questions.  See, for example, California Law Attempts to Prevent Marijuana Use While Driving, Is it Possible to Prove "Driving Under the Influence of Drugs? and Legal Defenses to a California DUI of Marijuana.  

Unlike with alcohol, the various states have taken a variety of different approaches to criminalizing marijuana and driving.  See What Are Your State’s Drugged Driving Laws?   One recent and growing approach is to simply create so-called "per se" laws which criminalize driving with specific levels of THC in the blood, regardless of impairment.  This was recently considered by the Oregon Legislature, resulting in the following Oregon House Bill Legislative Report, excerpts of which follow:


Salem, OR.  Dec. 31 —  …While Colorado and Washington, the first states to legalize recreational marijuana, instituted a per se THC blood concentration limit of 5 ng/ml, Oregon did not. Instead, Oregon relies on evaluations by Drug Recognition Experts (DRE) to assess drivers for intoxication if they have already passed a breathalyzer test (i.e. have blood alcohol content below 0.08)….

Differences in how the body processes marijuana as compared to alcohol makes accurate detection of THC concentration and its intoxicating effect significantly more difficult. It is especially difficult to detect recent use of marijuana in the field… 

Due to restrictions on cannabis research and limited data, it is difficult to make definitive statements about the risk of THC-intoxicated driving. The body of evidence that does exist indicates that while attitudes towards driving after marijuana use are considerably more relaxed than in the case of alcohol, the risk of crashes while driving under the influence of THC is lower than drunk driving. Little evidence exists to compel a significant change in status quo policy or institute a per se intoxication standard for THC.


While the confusion, floundering and passage of inconsistent laws continue, so do the arrests and convictions of innocent drivers. 
 

What Are Your State’s Drugged Driving Laws?

"Drunk driving" is a fairly well-defined criminal offense in all 50 states.  There are generally two crimes set forth by statute:  (1) driving a vehicle under the influence of alcohol and (2) driving a vehicle with a blood-alcohol content of .08% or higher.  The only differences are in relatively minor variations as to what a "vehicle" is and what constitutes being "under the influence".

In marked contrast, however, the definitions of driving under the influence of drugs (so-called "drugged driving" or "DUI drugs") vary significantly from state to state.  In one state, for example, the crime consists of driving while "impaired by" or "under the influence of" a drug.  In another, it may be defined as driving with a specifically designated amount of the drug in the blood.  In yet another, the offense is committed if there is any measurable amount of the drug in the body — and in some states this will include marijuana, while in others it does not.

Do you know what the drugged driving laws are in your state?

Fortunately, the National Alliance for Model State Drug Laws (NAMSDL) in Charlottesville, Virginia, supported by  grant from the U.S. Office of National Drug Control Policy, has provided a chart entitled State Drugged Driving Standards which readily identifies the laws of each state.    
 

Medical Marijuana Patients Can Now Fight DUI Charges in Arizona

A recent decision by the Arizona Court of Appeals held that medical marijuana patients who have been arrested for driving under the influence of marijuana can fight the charges by arguing that they were not stoned enough to drive.

In 2013 Nadir Ishak was stopped by Mesa police when they saw his vehicle drift into another lane. The officer who arrested Ishak testified that Ishak admitted to using marijuana that morning and that his eyes were bloodshot and watery.

It was later determined that Ishak had a concentration of 26.9 nanograms of tetrahydrocannabinol (THC) per milliliter of blood.

Ishak was charged with driving while impaired and driving with marijuana in his system. During trial, Ishak wanted to inform the jury that he possessed a state-issued medical marijuana card at the time of his arrest. The trial judge, however, denied his request. The trial judge also determined that Ishak bore the burden of proving that he was not under the influence. Ishak was subsequently convicted and sentenced to 90 days in jail.

Ishak appealed arguing that the denial prevented him from having a fair trial.

The Arizona Court of Appeals, in a 2-1 decision, agreed with Ishak and concluded that the jury should have been made aware that Ishak was medical marijuana user. Additionally, the court also concluded that prosecutors, not defendants, must prove that a medical marijuana license-carrying driver was actually under the influence of the marijuana, not merely driving with the drug in their system.

In 2010, Arizona voters approved the Arizona Medical Marijuana Act which does not absolve stoned drivers from being charged for driving under the influence of marijuana. However, the Act also said that a medical marijuana user cannot automatically considered under the influence of the drug “solely because the presence of metabolites or components of marijuana that appear in insufficient concentration to cause impairment.”

What’s more, the Arizona Supreme Court in 2015 held that medical marijuana users charged with a DUI can argue “that the concentration of marijuana or its impairing metabolite in [his or her body] was insufficient to cause impairment.”

The prosecutor in Ishak’s case argued that the Arizona Medical Marijuana Act requires medical marijuana users who are arrested on suspicion of driving under the influence prove through expert testimony that the THC in their system was insufficient to cause impairment. He also argued that it is irrelevant whether Ishak was actually impaired.

What ever happened to the fundamental canon of American criminal jurisprudence, “innocent until proven guilty?” Although I can’t say that it surprises me that a DUI prosecutor would actually argue “guilty until proven innocent.”

Fortunately, however, Arizona Appellate Judge Diane Johnson, who wrote for the majority, disagreed with the prosecutor.

"Nothing in the statute … requires a cardholder to present expert testimony (or precludes a cardholder from offering non-expert testimony) on the question of whether the cardholder was impaired due to THC,'’ wrote Johnson. "And, according to evidence here, there is no scientific consensus about the concentration of THC that generally is sufficient to impair a human being.”

I’m happy to say Judge Johnson got it right.

California Law Attempts to Prevent Marijuana Use While Driving

As many of you now know, California passed proposition 64 this past November making recreational marijuana use and possession legal. According to Senator Jerry Hill, D-San Mateo, and Assemblyman Evan Low, D-Campbell, proposition 64 contains a loophole that they intend to close.

Last week, the legislators introduced Senate Bill 65 which will criminalize smoking marijuana while driving. Although Proposition 64 legalized the recreational use and possession of marijuana, it still made it illegal to have an open container of marijuana in a vehicle. Proposition 64 did not, however, address the use of marijuana while driving according to Hill and Low.

If you recall from previous posts, Hill has been known to introduce legislation aimed at preventing drunk driving. Last year he passed a law requiring ignition interlock devices for convicted drunk drivers who wished to reinstate their licenses.

“I have a real passion for solving our impaired driving in California from substance abuse,” Hill said. “I don’t want to go in a positive direction on one end and open up the door for deaths on the other end.”

One complaint that opponents have to Senate Bill 65 is that it also bans consumption of cannabidiol, the component of marijuana which is often used by those suffering from chronic pain or to alleviate the symptoms associated with cancer. Cannabidiol does not contain THC (tetrahydrocannabinol), which is the chemical in marijuana that causes impairment.

As I see it, another problem with Senate Bill 65, if passed, is that if a person is arrested for driving while smoking marijuana, they will also inevitably be arrested on suspicion of driving under the influence of marijuana. While a person may have been caught smoking while driving, it doesn’t necessarily mean that they are “under the influence” of marijuana.

To be under the influence of marijuana, the person’s use of marijuana caused their mental or physical abilities to become impaired such that they can no longer drive a vehicle with the same caution of a sober person, using ordinary care, under similar circumstances.

While police can utilize field sobriety tests, if the person agrees, to assess whether motor skills are impaired, there is no way to determine how “high” a person is after smoking marijuana. As I’ve said in many previous posts, this is different from alcohol where these is a correlation between a person’s blood alcohol content and impairment. No such correlation exists with marijuana.

Therefore, if Senate Bill 65 is passed, a person arrested for smoking while driving not only faces misdemeanor charges under that law, but they can also inevitably expect DUI of marijuana charges as well.

You can be sure I’ll be keeping my eyes on the progress of this one.