Chronic[les]: The Drugged Driving Fallacy

An immediate and enthusiastic cry from the anti-marijuana camp when states began to legalize recreational weed was that we would be waylaid with scores of Driving Under the Influence of Drugs (DUID) arrests and/or accidents. People correlated the availability of legal weed with an expected uptick in DUIDs, and that's not an unreasonable conclusion to draw. However, much of our legislation is based upon what we think will occur rather than actual history. Legislators, from any perspective, are struggling to keep up with, and define, the problem of the DUID.

CNN has published another riveting article on the evolution of marijuana culture in the United States, this time citing a published study that examines the relationship between fatal accidents and drug intoxication. So here are the brass tax, as it were.

Page 7 of the report (press release) has an infographic that breaks things down rather succinctly:

• 57% of fatally injured drivers were tested for drugs
• 34.3% of those tested were positive for drugs listed in the Fatality Analysis Reporting System (FARS), which includes marijuana
• 35.6% of those who tested positive for FARS listed drugs were positive for marijuana
• Reporting is based on the results of blood tests taken after fatalities occurred

It's worth it to do a little math with those numbers. Lets suppose that 57% testing is a good cross section of fatalities to examine. 12.2% of the population who were involved in a fatal car accident were positive for marijuana use. This is also consistent with the report's findings with respect to positive drug tests conducted because of sobriety check points. Were any of the drivers high at the time, though? Actually... impossible to tell.

This is the problem the states have with defining DUID. Testing positive for THC (psychoactive chemical in weed) only speaks to the presence of the drug. It is not conclusive of intoxication, proximity of use to the time of the accident, or causative relationship. The study is conspicuously silent on the issue of alcohol intoxication coexisting with suspected drug intoxication. Because the half life of THC in the blood stream is between four and twelve hours, there is an exceptional window in which to label a person as "impaired" when they may in fact have been well beyond any intoxicating effects.

Alcohol, on the other hand, metabolizes at a predictable rate with predictable effects on driving abilities. Any given person at a given Blood Alcohol Content (BAC) will have predictable symptoms. It can also be calculated how quickly a person will be over those symptoms, so even if a blood test occurs well after an event, determining BAC at the time is simple middle-school math.

The NHTSA, who performed this study, has a remarkable amount to say which was not included in the linked press release. Consider the following:

• 23,000 vehicle fatalities in 2015
• 17,000 involved the death of the driver
• 6,400 drivers had a BAC over .08%

If you whipped out the calculator, you will see that 36% of drivers killed in car accidents were drunk at the time. That number could easily encompass the 12.2% of drivers who tested positive for marijuana, but for whom alcohol involvement is not identified. Considering a Gallup poll that identifies 13% of the population to be current pot users, that number is statistically below mean. Not worth noting.

The NHTSA study quite clearly quantifies the risk of cannabis-only related crashes as "slight." Complimenting that is a 2012 study by Rune Elvik, Risk of Road Accident Associated With the Use of Drugs. Elvik found that the ratio of fatal accidents occurring among cannabis users was 1.31:1. That's practically an even chance. Alcohol, by comparison, is at least a 3:1 ratio in the best performing demographics (age 35 and above), and as high as 14:1 among teens.

The repeated conclusion is that marijuana intoxication does not present a significant risk to driver safety. It's groundless to claim otherwise. The scientific data just doesn't support the assertion that stoned drivers are dying in any significant numbers. That warning cry mentioned at the outset is just without foundation. Was it a good idea to be cautious? Certainly! But it just didn't manifest the way the nay-sayers feared. Advocacy groups, however, rarely have the humility to label themselves as alarmists, let alone wrong.

We are all familiar with the effects of drunk driving. That has been very well studied for decades. The experience we rely on in determining the threat presented to the public happens to be the only tool in the toolbox, unfortunately. And to police who only have a hammer, every driver looks like they need to be nailed.

Of course we all know that it's unwise to operate a car when our senses are affected. We learn to drive with unaltered sensory perceptions. It is only reasonable to conclude that any change to that presents a different risk. However, there are chemical and non-chemical distractions in this world that far eclipse the risks associated with marijuana intoxication.

The risks associated with drunk driving, texting and driving, and teen driving don't prompt us to outlaw booze, cell phones, or young people. Compounding the problem defining intoxication is that the interim demands some kind of stop-gap measure. Driving impaired is negligent to the safety of others, which is deserving of adjudication. But the determination of negligence can only be made by law enforcement who have only the most arbitrary of guidelines. I would personally like to think that if I were subject to legal penalty, my infractions would be very well defined.

Such as it is, the law and good citizenship demands that we do something, even if it's incorrectly scaled.