Marijuana DUIs
It is becoming more and more common for people to be arrested for driving under the influence of Marijuana (Cannabis). One of the reasons for this is that more police officers are getting certified as Drug Recognition Experts (DREs).
A DRE is an officer that has received advanced training to determine if a driver is impaired by drugs. In order to do this, they are supposed to conduct a (12) step evaluation of the subject. This process is Standardized and Systematic, which means that it is supposed to be done the same way every time. At the end of the evaluation the DRE determines (3) things; is the subject impaired and is the impairment consistent with the subject BAC? Is the impairment injury, illness, or drug related? If drug related, what category (or categories) of drugs is (or are) the likely cause of the subject’s impairment?
How accurate are DREs? To become certified they only have to be accurate 75% of the time. This means that they can be completely wrong on 1 out of 4 people and still become certified. A laboratory study from (1998) dosed volunteers with several different types of drugs. Some volunteers were also given placebos, which means they had no active drugs in their system. The DREs incorrectly concluded that 28% of the placebo dosed subjects were impaired. This means that subjects that had absolutely no drugs in their system were wrongly classified as impaired. This shows that the DRE program is not perfect, and this may amount to reasonable doubt in court.
It should be no surprise that some people that have been arrested for DUI Marijuana have had clean blood and urine tests. The problem with marijuana is that there is no accurate indicator.
DREs are taught that the eyes don’t lie, so they should trust the eye tests. What eye tests do DREs use? They use Horizontal Gaze Nystagmus (HGN), Vertical Gaze Nystagmus (VGN), Lack of Convergence, Pupil Size Estimation and Reaction to Light.
This is where the problems begin. Marijuana has no expected affect on HGN, VGN, or Reaction to Light. Marijuana may cause the pupils to dilate (become larger), but it also may not. The pupils also dilate in dark lighting, so this will naturally occur during most nighttime DUI investigations. Now we are down to the last test, Lack of Convergence. This simply means that a person is unable to cross their eyes.
Marijuana does cause Lack of Convergence, but approximately 10% of the otherwise normal population cannot converge their eyes when sober. This means that 1 out of 10 people will have this indicator while completely sober. This is definitely not an indicator that can be truly relied upon.
There are many other tests that DREs use including; Modified Romberg Balance, Walk and Turn, One Leg Stand, and Finger to Nose. The problem is that none of these tests have been validated to indicate impairment from marijuana. The manual does not tell the DRE what the results of these tests specifically indicate in relation to marijuana (i.e. 2 or more clues on the Walk and Turn indicates Cannabis impairment with **% accuracy). This means that it is up to the individual DRE’s discretion as to what the test results indicate. This part of the testing is not “Standardized.”
What if the Blood or Urine test comes back positive for THC (Tetrahydrocannibinol) or the active metabolite Hydroxy THC? Studies show that THC level in a person’s blood is not an accurate and reliable predictor of impairment from marijuana.
Doesn’t THC or Hydroxy THC in the person’s blood indicate recent use? Not necessarily! A study was conducted on chronic marijuana users. They abstained from marijuana usage for (30) days. At the end of the (30) days their blood was tested. Some still tested positive for THC after (30) days of abstaining.
If you or your client has been arrested for DUI Marijuana, have your case reviewed by a former Drug Recognition Expert Instructor to see if there are issues with your case.
About the author: Joshua Ott operates Caselock Inc., specializing in expert testimony and reviews for cases involving alcohol and/or drug impairment. Joshua has extensive knowledge and training obtained from ten years as a police officer in Metro Atlanta. He has extensive experience training law training law enforcement officers as well as courtroom preparation and testimony. He resides in Woodstock, Georgia with his wife, daughter and Miniature Schnauzer, Gus. For more information, visit caselockinc.com.