DUI Defense
DUI in Tennessee is not just about alcohol. You can be charged with driving under the influence of marijuana, prescription medication — even medication you take exactly as your doctor prescribed — or any other intoxicant if the State claims it impaired your ability to drive. These cases are tried on very different evidence than alcohol cases, and they are frequently more defensible than people assume. Brooks Law Firm defends drug-based DUI charges in Memphis, Shelby County, and West Tennessee. Call (901) 324-5000.
Wondering what this will cost? See how much a DUI lawyer costs in Memphis — flat fees by court, and what a DUI trial runs.
Why Drug DUI Cases Are Different
Alcohol has a legal number — .08% — and a machine that claims to measure it. Drugs do not. There is no per se legal limit for THC or most other substances in Tennessee, so the State must prove actual impairment at the time of driving, usually through officer observations, field sobriety tests designed and validated for alcohol, and a blood result that shows presence, not impairment. THC in particular can remain detectable long after any effect has passed, which means a positive blood test alone does not prove an impaired driver. That gap between presence and impairment is where these cases are fought.
Prescription Medication Cases
A valid prescription is not a complete defense to DUI in Tennessee — but it changes the case. Prosecutions built on therapeutic levels of a lawfully prescribed medication invite hard questions the State often cannot answer: what level causes impairment in this patient, what tolerance does a long-term patient have, and what did the officer actually observe that ordinary fatigue or anxiety would not explain. We review the toxicology, the officer’s training in drug recognition, and the video in every case.
The Evidence We Challenge
Drug DUI cases get the same constitutional and scientific review as any other DUI we handle: the basis for the stop, the field sobriety testing, the legality of the blood draw and its chain of custody, the TBI laboratory analysis, and the qualifications of any officer offering impairment opinions. Patrick Brooks is a member of the National College for DUI Defense (NCDD) and TACDL, and applies the current science of drug toxicology and impairment to these cases. Where drug charges accompany the DUI — possession found during the stop — we defend both cases together, because the suppression issues usually overlap.
Blood Tests and the Right to Refuse
In a drug case the State’s chemical evidence is usually a blood test, because the breath machine is built for alcohol. Knowing what the law allows helps you make sense of what happened at the roadside or the hospital, and it tells us where to look first.
Tennessee’s implied-consent law covers breath and blood tests. If an officer with probable cause arrests you, asks for a test and warns you of the consequences, and you refuse, the judge decides whether you refused, on a warrant separate from the DUI. A refusal is not a crime, but it costs the license. A first refusal means one year, or 18 months since January 1, 2026 for refusing a blood test when a misdemeanor DUI is suspected. From January 1, 2027, every first refusal by a driver without a prior conviction will mean 18 months (T.C.A. §§ 55-10-406, 55-10-407). More on refusing a test in Memphis.
Refusing does not stop the test. The officer can seek a search warrant, and since May 2025 the refusal still counts even when blood is then drawn under one. In some situations a test is mandatory, by warrant or under exigent circumstances, whether or not you agree. That applies after a crash that injured or killed another person, with a child under 18 in the vehicle, or when the driver has a prior DUI, vehicular assault or vehicular homicide conviction (§ 55-10-406(c)). A driver who is unconscious cannot be blood-tested without a warrant or exigent circumstances (§ 55-10-406(f)).
What to do now: while you still remember, write down where and when your blood was drawn and who drew it. List every prescription, over-the-counter medicine and other substance you had taken in the days before, with the times. In a drug case the question is not whether something was in your blood but whether it was affecting your driving at that moment, and timing is often where that question is answered.
Common questions
Can I refuse a saliva (mouth swab) test?
Yes, and refusing one is not an implied-consent violation, because implied consent covers only breath and blood. Since May 2025, though, police can take an oral-fluid test with your consent, a search warrant, incident to a lawful arrest, or in exigent circumstances, and the result is admissible at trial (§ 55-10-406(b)(3), (j)(2)).
Is a drug DUI punished differently from an alcohol DUI?
The DUI statute sets no separate penalty for drugs. A first conviction carries at least 48 consecutive hours in jail, a fine of $350 to $1,500 (§ 55-10-403) and a one-year license revocation (§ 55-10-404). DUI is excluded from both pretrial and judicial diversion, and a conviction cannot be expunged absent a governor’s pardon (§ 40-32-107(d)). A dismissed DUI charge can be expunged at no cost.
I used a legal hemp product. Can that still be a DUI?
Yes. Since January 1, 2026, adults 21 and older can buy regulated hemp-derived products from licensed retailers, but the hemp law says expressly that it does not authorize impaired driving (§ 57-7-111). The product being legal is not a defense by itself. The State still has to prove you were impaired, and that is where these cases are fought.
The officer found my prescription pills in the car. Is that a separate charge?
Simple possession under § 39-17-418 does not cover a controlled substance you obtained under a valid prescription. Keep the pharmacy records and your prescribing doctor’s information. They matter to the possession question and to the DUI, where your dosing history and tolerance are part of the defense. More on prescription pill charges.
What if my blood test came back negative?
Then the State’s case rests on the officer’s observations and the video, which is a very different case to defend. A negative result does not end the case automatically, but it takes away the chemical evidence.
If you have been charged with driving under the influence of marijuana, prescription medication, or any other substance in Memphis or the surrounding counties, call Brooks Law Firm at (901) 324-5000 for a free consultation. See also: Memphis DUI defense and what happens after a first DUI.