Can Police Prove Marijuana DUI? Challenges Compared to Alcohol Cases

Yes, prosecutors can try to prove marijuana DUI — but proving it beyond a reasonable doubt is another matter. Unlike alcohol, there is no reliable Breathalyzer for marijuana. Although researchers are developing one, it will likely not be available for years. Until then, Georgia prosecutors must rely on circumstantial evidence such as officer observations, field sobriety tests, or blood results — all of which are often shaky and open to challenge in court.

Blood test evidence can, in theory, be used in marijuana DUI cases. But officers generally need a warrant to draw blood if a driver refuses to consent — and in practice, police rarely go through this extra step. This makes marijuana DUIs far harder to prosecute than alcohol-related cases.

If no chemical test is available, the state’s chances of securing a conviction drop sharply — and that gives us more room to protect you. A first-time DUI conviction can cost you more than $10,000 once fines, fees, and collateral expenses are added up. With so much on the line, you shouldn’t face these charges alone. At Zimmerman & Associates, our criminal defense lawyers know how to challenge weak evidence and fight for the best possible outcome in your case.

Field Test Evidence

If police officers have probable cause to believe that the defendant is under the influence of marijuana, they can administer field sobriety tests.

For many years, the “I smelled marijuana” line justified countless DUI, drug possession, and other criminal investigations. But hemp, which is physically identical to marijuana, is legal. So, the odor of marijuana could be the odor of hemp. As a result, a good defense lawyer might be able to get the investigation thrown out of court.

If the judge allows FST results, prosecutors are not out of the woods. These tests, which have questionable scientific foundations, have some serious flaws.

• HGN: During the Horizontal Gaze Nystagmus, or DUI eye test, officers look for involuntary pupil movements that indicate the presence of nystagmus. Specific drug use, like marijuana use, causes nystagmus. However, the leading cause of nystagmus is a childhood brain injury.
• W&T: The Walk and Turn is a divided attention test that measures physical dexterity and mental acuity. Scientifically, intoxicated persons cannot walk and chew gum at the same time. So, officers look for mental clues, such as taking the wrong number of steps, and physical clues, such as swaying while walking heel to toe. Unless the subject is wearing athletic shoes, it is almost impossible to walk a straight line from heel to toe.
• OLS: The One Leg Stand test is very similar to the W&T test. Officers look for physical clues, such as using arms for balance while standing on one leg. By the time officers administer the third test in the three-test battery, suspects are mentally and physically fatigued and unlikely to pass a test like the OLS, whether they are drunk or sober.

Frequently, a Georgia criminal defense lawyer partners with an expert who highlights these flaws and others to jurors. At that point, many jurors believe that the state is trying to railroad the defendant.

Non-Field Test Evidence

Defendants have a Fifth Amendment right to refuse to perform FSTs. If they do so, the state must rely on even weaker circumstantial evidence and/or testimony from a DRE (drug recognition expert).

The weaker physical evidence includes bloodshot eyes, erratic driving, and other physical symptoms that could be caused by intoxication. Another condition, such as fatigue, could also cause them. Since the burden of proof is so high, prosecutors cannot leave it to jurors to connect the dots.

Many Georgia law enforcement offices now employ DREs. Despite the official-sounding name, a DRE is essentially a police officer who has taken some extra classes over the weekend. The testimony of a DRE usually pales in comparison to the testimony of a degreed scientist, as mentioned above.

Reach Out to a Thorough Gwinnett County Attorney

DUI crimes have significant consequences. For a confidential consultation with an experienced marijuana DUI defense attorney in Norcross, contact Zimmerman & Associates. The sooner you reach out to us, the sooner we start working for you.