Understanding the Risks of Driving High

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The debate over whether driving while high is as dangerous as driving while intoxicated is ongoing, with both sides fiercely defending their position.

It should be clear to any driver that getting behind the wheel while impaired—no matter the substance—is never a good idea. Marijuana has been shown to slow a driver’s reaction time, impair time and distance judgments, and decrease coordination—although these responses typically occur within a few hours of use.

Those using cocaine or methamphetamine could be aggressive, and even reckless while driving. Prescription drugs come with their own set of physical symptoms; as an example, some sedatives called benzodiazepines can cause drowsiness and dizziness.

And, of course, alcohol can slow reflexes, impair vision and the ability to judge the position of cars and road signs and can adversely affect concentration, the ability to make rational decisions, and coordination. 

How Many Drivers are Under the Influence of Drugs or Alcohol?

Some studies have shown an increase in lane weaving, altered attention to the road, and poor reaction times among those using marijuana, and, when marijuana was mixed with alcohol, those effects became more pronounced.

Depending on the person, as well as the specific drugs, alcohol, or drug and alcohol mixture in the body, a measurable effect may be seen when that person decides to get behind the wheel.

A 2014 National Survey on Drug Use and Health found that about 27.7 million people above the age of 16 had driven while under the influence of alcohol within the past twelve months.

That number was 10.1 million for illicit drugs (This particular study did not include prescription drug use while driving). This same study found that:

  • Men are more likely than women to drive while impaired;
  • After alcohol, marijuana is the drug most often found in the blood of drivers who are involved in an automobile collision;
  • More young adults (those from 18-25) drive while impaired than adults who are 26 or older;
  • A different, 2010 study, found that 47 percent of those who tested positive for drugs had used a prescription drug, as opposed to about 37 percent who used marijuana, and 10 percent who used cocaine, and
  • The most common prescription drugs found in the systems of those who were driving under the influence were pain relievers. 

Role of Marijuana in Car Collisions Remains Unclear

Despite the statistics, the role marijuana plays in crashes is unclear, primarily because THC can be detected in body fluids for days, even weeks after use.

Further complicating the issue is the fact that alcohol is often used in conjunction with marijuana. While some studies concluded a driver with THC in his or her blood was roughly twice as likely to be responsible for a fatal auto accident, a large NHTSA study found there was no significantly increased collision risk which could be definitively tied to marijuana use.

A CBS news report essentially concluded that driving while high was simply not as dangerous as driving while under the influence of alcohol.

In fact, unlike alcohol, which is well-known to increase risk-taking behaviors among those who drink and drive, the impact of marijuana on psychomotor skills is far more subtle.

In fact, the CBS news article stated the reason marijuana is the most common illicit substance consumed by those who admitted to driving after drug use, is because nearly one out of every two people over the age of 16 have used marijuana.  

That being said, the risk of driving while under the influence of marijuana “…is far lower than the fatality risk associated with drivers who operate a vehicle with the presence of alcohol in their system.”  

The Effects of Marijuana on Car Crashes Nearly Impossible to Quantify

Because THC can be present in the blood for an extended period after actual use (long after the impairing effects have worn off), the presence of marijuana in toxicological evaluations of U.S. drivers does not necessarily indicate that marijuana use is a causal factor in car collisions.

In fact, states which have legalized medical marijuana have experienced little or no corresponding rise in traffic fatalities. The effects of marijuana use on psychomotor performance can vary widely from person to person, particularly between those who are “new” marijuana users and those who have used marijuana as a recreational drug for months or years.

Further, the actual impairment period of marijuana is relatively short-lived, meaning consumers of marijuana can greatly reduce their risk of an auto accident by staying off the road for several hours following their use of the drug.

Increasing Efforts to Train Police Officers to Identify Impaired Drivers

There is currently no test which can be used to test a driver for recent marijuana use. There is a push within the law enforcement community to better train their officers to identify those drivers who could be driving while high or under the influence of other drugs, whether illicit or prescription.

The Standardized Field Sobriety Tests could see changes which would allow officers to determine cannabis use, and the development of a roadside, cannabis-specific detection test (similar to a breathalyzer) is in the works.

Due to the nature of marijuana, tests which determine recent use as opposed to use which could have occurred weeks ago, are necessary.

In the end, drivers should avoid driving under the influence of any substance, as a means of decreasing auto accidents.

Have you tried driving high? Share your experience in the comments section below.

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