DUI Defense – Medical Marijuana v. Alcohol


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Medical Marijuana DUI cases in Arizona have two fundamental differences from DUI Alcohol cases which help the Medical Marijuana DUI defense at trial.

 

With Medical Marijuana DUI cases now going to trial and in some cases the State seeking to prove to the jury the Marijuana (THC) levels found in the defendant’s blood, it is important to remember the obvious namely, the issue is the levels of the marijuana at the time of driving or being in actual physical control, and not, as with alcohol, “within two hours” of driving or being in actual physical control.

 

The Arizona Legislature has written the DUI Alcohol statutes so all the State must prove to the jury is what the alcohol levels were “within two hours” of driving or being in actual physical control.  The Arizona Legislature however has never said the “within two hours” rule applies to Drug DUI cases including Medical Marijuana DUI cases.  Since the Legislature has never applied the “within two hours” rule to Drug DUI cases, according to a 1989 Arizona Supreme Court case, Desmond v. Superior Court, 161 Ariz. 523, the issue is, the levels of drugs in the blood at the time of driving or being in actual physical control and not when the blood is drawn.

 

Using a scientific principle known as “Retrograde Analysis” it may be possible to for an expert witness to calculate what a person’s alcohol level is, or certain drug levels, at an earlier point in time.  To make the calculation for alcohol the expert would need to know such information as, what the test results were and when the person stopped drinking.  For example if a person had an alcohol test result (or blood draw) showing a level of .20% at 9:00 p.m. and stopped drinking at 6 p.m., it may be possible for an expert to calculate what the person’s alcohol level was at an earlier time,  say, 8:00 p.m.  One of the reasons a retrograde analysis is possible with alcohol is although rates of absorption of alcohol into the blood may vary, most of the alcohol ingested is absorbed relatively easily into the blood.

 

Expert witnesses say however that a “Retrograde Analysis” is not scientifically possible with Marijuana.  That is in part because THC, the active ingredient of Marijuana, is not absorbed into the blood as easily as is alcohol, and so the same underlying principles needed for a Retrograde Analysis are not present for Marijuana.

 

Legally not being able to do a retrograde analysis is very important for Medical Marijuana DUI cases.  Remember, the issue is the marijuana level at the time of driving or being in actual physical control and not when the blood is drawn.  The Desmond case says if the State wants to tell the jury what the marijuana levels were it must show the levels at the time of driving or being in actual physical control and not simply when the blood was drawn.  Demond also says the State must use a retrograde analysis to relate the test results to the time of driving.  However, the experts say scientifically it is not possible to do that needed retrograde analysis with marijuana.  Desmond also says that if the State cannot do a retrograde analysis to the time of driving or being in actual physical control then the State may only tell the jury that marijuana was present at the time of the blood draw, but not what the levels were at the time of the blood draw, or the time of driving, or being in actual physical control.

 

In many cases the evidence is much better for the defendant when the jury cannot be told what the marijuana levels were.

 

So for two reasons Medical Marijuana DUI cases have a better defense which is not available in DUI Alcohol cases.  First, the issue is what the marijuana levels were at the time of driving or being in actual physical control, and not within two hours.   Second, scientifically it is not possible to show what the marijuana level was at the time of driving.

 

Gordon Thompson

 

For more information about Arizona dui and criminal law issues please contact Gordon Thompson who has used his experience to write a blog on topics of interest. You can also chat with Gordon about your specific questions.   Website:  https://GordonThompsonAttorney.net