Drug DUI Prosecution in Georgia

Georgia prosecutes drug-impaired driving under two distinct legal theories housed within the same DUI statute, O.C.G.A. § 40-6-391. The two theories require proof of very different things, and the distinction between them shapes how a drug DUI case is built and what evidence matters most.

The Less-Safe Theory

Under § 40-6-391(a)(2), the state must prove that the driver was under the influence of a drug, whether illegal, prescription, or over-the-counter, to a degree that rendered the driver less safe to operate a vehicle. Unlike alcohol DUI, where a blood-alcohol concentration at or above a set level can establish a per se violation, there is no equivalent concentration threshold for most drugs under the less-safe theory. The state must instead prove actual impairment through other evidence, such as an officer’s observations of driving behavior and physical signs of impairment, performance on field sobriety evaluations, and, where used, the assessment of a trained Drug Recognition Evaluator.

The Per Se Controlled Substance Theory

A separate provision, § 40-6-391(a)(6), establishes a per se violation: the presence of any detectable amount of marijuana or a controlled substance listed under O.C.G.A. § 16-13-21 (the schedule of controlled substances) in a driver’s blood or urine, including metabolites and derivatives of those substances, is sufficient by itself to establish the offense. Under this theory, the state does not need to prove that the driver was actually impaired at the time of driving. The presence of the substance, or its metabolite, is enough.

The Metabolite Issue

This per se structure creates a substantive distinction that is easy to overlook. Marijuana metabolites, particularly THC-COOH, can remain detectable in urine for an extended period after use, well beyond the window during which any impairing effect would be present. A driver who used marijuana days earlier, with no impairing effect remaining at the time of driving, could still test positive for the metabolite and face a per se charge under (a)(6), because the statute’s “any amount” standard does not distinguish between a metabolite reflecting recent impairing use and one reflecting past use with no current effect.

No Minimum Concentration Threshold

Some states set a specific concentration threshold, such as a defined nanogram-per-milliliter level of THC in blood, before a driving-under-the-influence-of-marijuana charge can proceed on a per se basis. Georgia has not adopted a comparable minimum concentration threshold for marijuana or other controlled substances under § 40-6-391(a)(6). The statute’s “any detectable amount” language is, as written, an absolute standard rather than a threshold-based one, which is a meaningful difference from jurisdictions that calibrate per se liability to a specific measured concentration.

Drug Recognition Evaluators

Georgia law enforcement uses officers trained as Drug Recognition Evaluators, following the structured evaluation protocol developed through the national DRE program, to assess and categorize suspected drug impairment in the field. A DRE evaluation typically involves a multi-step physical and behavioral assessment intended to identify which category of drug, or combination of drugs, may be affecting a driver. DRE findings are most often used to support the less-safe theory of prosecution, particularly in situations where chemical testing is unavailable, delayed, or inconclusive on its own.

A Prescription Does Not Provide Automatic Protection

Holding a valid prescription for a medication does not categorically prevent a drug DUI charge. Section 40-6-391(a)(2) applies to impairment caused by any drug, including one that was lawfully prescribed and lawfully taken, if the state can establish that the medication rendered the driver less safe to operate a vehicle. The lawful nature of the prescription speaks to how the substance was obtained, not to whether its effect on the driver’s ability to drive safely meets the statutory standard.

Two Theories, One Statute

Because both the less-safe and per se theories live within the same DUI statute, a drug DUI case may be charged, and in some circumstances prosecuted, under either or both theories depending on the available evidence. The less-safe theory turns on demonstrated impairment; the per se theory turns on the chemical presence of a prohibited substance or its metabolite, regardless of whether impairment can independently be shown.

This article provides general information about Georgia law and is not legal advice. Consult a licensed Georgia attorney about a specific situation.