How Do Police Test for Weed DUI in Tennessee?
The Law Offices of Adrian H. Altshuler & Associates have over 25 years of criminal defense experience. Keep reading to learn more about how police test for weed DUI in Tennessee and how a lawyer with our firm could help you build a case and fight your charges.
Marijuana DUI in Tennessee – what you need to know
Marijuana use is illegal in Tennessee, both for medical and recreational purposes. It is also illegal to drive under the influence of “any intoxicant,” including weed and other drugs, that impairs a driver’s ability to safely operate their vehicle.
A drug DUI in Tennessee carries the same criminal penalties as an alcohol DUI. If convicted, a first offense could result in a mandatory minimum of 48 hours in jail (up to 11 months and 29 days maximum), up to $1,500 in fines, and a one-year revocation of your driver’s license. A judge must also impose certain probation conditions, which may include DUI school and a drug-and-alcohol assessment or treatment, or a victim impact panel; community service may also be ordered. The punishments increase if you have prior DUI convictions.
A DUI lawyer could help you if you face marijuana DUI charges. They could work to lessen the impact of your case on your life.
Drug DUIs could also lead to other drug charges
Marijuana is illegal in Tennessee, so if police find it (or any other illegal drugs) on you or in your car during a DUI stop, you could face charges for other drug crimes. This could include charges for possession and/or intent to sell that can result in steep fines and imprisonment if found guilty.
How do police test if someone is driving while high?
First, it is important to understand that before pulling you over, the police must have a reason. Actions that could cause them to stop you include speeding, swerving, or running red lights or stop signs. If, during the stop, police observe signs of impairment that establish probable cause, they could request or lawfully obtain cannabis testing.
There are several ways cops test for a weed DUI, including:
Field sobriety testing
The police may conduct standardized field sobriety tests (SFSTs). The officer will ask you to stand on one leg for around 30 seconds and to walk in a straight line and turn. They may also check for horizontal gaze nystagmus (HGN), or involuntary jerking as your eyes track an object from side to side, like a pen.
Evaluation by a drug recognition expert (DRE)
The officer who pulls you over may call in a DRE. A DRE is an officer with special training on how to recognize the signs of marijuana intoxication and other substances. The DRE will conduct an evaluation that usually involves 12 steps and can take up to an hour.
Blood, saliva, or urine testing
The cops can test bodily fluids for THC. Marijuana can stay in your system for a long time, and the different types of fluid tests have different detection times.
Blood tests may detect THC or its metabolites for varying periods; a positive result does not by itself prove when marijuana was used or that the driver was impaired. A blood draw must be performed by a qualified practitioner under lawful authority, so it is not performed as an ordinary roadside test.
Saliva tests may detect recent THC use, but the detection window varies depending on the test and the person’s use pattern. A positive test could provide evidence that you have consumed marijuana in the days before an officer stopped you, but it does not necessarily prove you were high while behind the wheel.
Urine tests may detect cannabis metabolites for days or weeks, depending on the test and the person’s use pattern. Like a blood test, a urine test is generally performed later rather than along the road during a traffic stop. And, like a saliva test, it does not definitively show that you were high and driving.
Finally, it is important to note that there is no per se limit for marijuana intoxication. Per se is a Latin phrase meaning “in itself.” In legal language, it is usually used to indicate an action that is automatically illegal. For example, the per se limit for alcohol is a blood alcohol concentration (BAC) of 0.08 percent or higher. If you drive or are in physical control of a vehicle with a BAC of 0.08 percent or more, you violate Tennessee’s per se DUI provision.
Can you get a DUI for driving on THCA or Delta-8?
As of July 1, 2026, Tennessee law restricts the sale of Delta-8 and THCA products, and some products are prohibited.
As with weed, if an officer suspects you of a THCA DUI in Tennessee, they may ask you to take an SFST, consult with a DRE, or seek legally authorized fluid testing.
What should you do after a DUI arrest?
If you have been arrested and charged with driving under the influence of marijuana in Tennessee, you should contact an attorney to discuss your case. You could face penalties that could result in fines or even imprisonment, and a DUI lawyer can help you construct a defense.
There are several grounds on which an attorney could help you fight your charges, including challenging the officer’s reasons for pulling you over or contesting the results of a bodily fluid test, which typically cannot show with 100 percent certainty that you were impaired while driving.
Reach out to the Law Offices of Adrian H. Altshuler & Associates
The Law Offices of Adrian H. Altshuler & Associates aggressively defend clients across Tennessee. We know how a weed DUI or other drug-related charge can upend your life, and we are here to help. We can develop a defense strategy tailored to your needs with the goal of minimizing the impact of your charges on you and your loved ones.
We have offices located in Franklin, Columbia, and Brentwood. We offer free initial consultations, so there is no risk in reaching out to us to learn more. Contact us today.