How Can the Police Tell if Someone Is Driving High?

Driving while under the influence of drugs or alcohol is never a good decision. When you decide to drive while impaired, you’re not only putting yourself at risk but everyone else around you as well. According to the CDC, in respect to drugs other than alcohol, accidents involving impaired drivers make up about 16% of all motor vehicle crashes in the United States. This applies to both legal and illegal drugs, including prescriptions. Additionally, the CDC reports that those driving high while under the influence of marijuana are 25% more likely to be involved in a collision. 

These are certainly concerning statistics, especially considering that these accidents are completely preventable. Even if you don’t find yourself in a motor vehicle accident while under the influence and behind the wheel, that doesn’t mean you are free from the consequences of your actions. Law enforcement officers are trained to spot the tell-tale signs of impaired driving long before disaster strikes. Law enforcement agencies rely on specially trained officers, known as drug recognition experts, to detect drivers who are behind the wheel while intoxicated. Read on to discover more about how police officers can tell if someone is driving high. 

There’s No Breathalyzer for Marijuana, So How Can Law Enforcement Tell if You’re Driving High? 

Detecting drivers who are under the influence of drugs can be a more complex process compared to detecting drivers who are under the influence of alcohol because there is currently no breathalyzer for marijuana. To combat this issue, many states throughout the country have begun to implement specially-trained law enforcement officers called drug recognition experts (DRE). 

Drug recognition experts follow the DRE protocol to determine if individuals are driving while under the influence of drugs. While DRE protocol can’t help officers determine what specific mind-altering drug a driver is using, whether it be methamphetamine, cocaine, marijuana, or another substance, this protocol can help officers identify the behavioral and physiological signs that indicate drug use. 

Is There a Standardized Measurement of THC in the Blood?

The standard practice of testing someone for marijuana is a threshold of 5 nanograms of tetrahydrocannabinol (THC)—the psychoactive compound in marijuana—per milliliter of blood. However, not every state in the U.S. has established what level of THC qualifies a driver as impaired. While the traditional 0.08% blood alcohol content (BAC) that indicates a driver is above the legal limit of alcohol consumption to operate a motor vehicle is scientifically backed, marijuana-defined impairment is not. 

As marijuana and other drugs react and metabolize differently in the body compared to alcohol, it is much harder to determine if an individual is currently high based on blood tests alone. Whereas one person may metabolize marijuana within hours, another person may still have marijuana in their system after several days or even weeks, meaning you could potentially face marijuana DUI charges even if you have not used marijuana on the day of your arrest. 

That is where DRE protocol comes into play, allowing officers to determine if a driver is high based on behavioral and physiological factors rather than on blood tests that may or may not be accurate. Check out the 12 steps that drug recognition experts follow to help determine if a driver is under the influence of drugs. 

12 Steps in the DRE Protocol  

After being pulled over by an officer on suspicion of being high while driving, the DRE officer will take the following 12 steps in the DRE protocol to help determine if you are, in fact, presently high. 

  1. The arresting officer will submit your breath alcohol test to the DRE. 
  2. The DRE will conduct an interview with the arresting officer, where they are informed about the nature of the arrest and the behavior of the suspect during the arrest.
  3. The preliminary examination includes both a medical evaluation to determine whether medical assistance is necessary as well as an observation of several factors. The DRE will observe the suspect’s attitude, breath, coordination, pupil dilation, facer, and speech. They will also check your pulse and perform a horizontal gaze nystagmus (HGN) test on your eyes.
  4. The DRE will conduct a more thorough eye examination, assessing for vertical gaze nystagmus (BGN) and a lack of convergence. 
  5. You will be put through four divided attention psychological tests, which will include the modified Romberg balance examination, the walk and turn examination, the one-leg stand examination, and the finger to nose examination.  
  6. The DRE will take your vital signs, including another check of your pulse as well as your blood pressure and temperature. 
  7. The DRE will conduct the dark room examinations where your pupils are examined under three types of light conditions. Your pupils will be categorized as dilated, normal, or constricted. 
  8. Your muscle tone will be examined as some drugs are known to make muscles loose and flaccid while others make muscles rigid. 
  9. Your pulse will be taken a third time, and the DRE will examine your skin for injection sites. 
  10. You will be given a chance to provide an official statement to the DRE. The officer will ask about any past or present drug history.
  11. The DRE will make an official opinion about whether they believe you are impaired based on their analysis of the results of the previous steps. They will declare which category of drugs are suspected if they believe you are impaired. 
  12. A final toxicological exam will be conducted in which your blood, urine, and/or saliva samples are taken for lab analysis. 

Avoid a Marijuana DUI

So, while it is much harder for law enforcement to determine if someone is driving high compared to driving drunk, the DRE has an extensive protocol in place that is used to find suspects guilty of being under the influence of drugs while operating a vehicle. At the end of the day, the best way to avoid having to deal with law enforcement and the DRE is to never drive while under the influence. If you have been drinking or using drugs, never get behind the wheel. It’s always best to call a friend or a rideshare service if you’re under the influence and need to get home. 

If you have been charged with driving high, a criminal defense lawyer can help. Your dedicated attorney will look for errors made by the arresting officer and DRE officers and build a solid defense in order to possibly have your charges reduced or even dropped.


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