DUI Prosecution Theories in Georgia

Georgia’s driving under the influence statute, O.C.G.A. § 40-6-391, does not set out a single way of proving a DUI charge. Instead, it establishes several distinct legal theories, each with its own elements and its own type of proof. Understanding how these theories differ is essential to understanding what a DUI charge in Georgia actually alleges, because the same underlying incident can sometimes be prosecuted under more than one theory at once.

The Less-Safe Theory

Under O.C.G.A. § 40-6-391(a)(1), a person commits DUI by driving or being in actual physical control of a moving vehicle while under the influence of alcohol to the extent that it is less safe for that person to drive. This is commonly called the less-safe theory. It does not require any specific blood alcohol concentration. Instead, the prosecution must prove impairment through other evidence, such as an officer’s observations of driving behavior, the odor of alcohol, slurred speech, balance or coordination issues, admissions made by the driver, and performance on field sobriety evaluations. The less-safe theory asks a factual question, whether the alcohol actually made this particular person less safe to drive, rather than relying on a fixed numerical threshold.

The Per Se Alcohol Theory

A separate theory appears in O.C.G.A. § 40-6-391(a)(5), which is commonly called the per se theory. Under this provision, it is illegal to drive with an alcohol concentration of 0.08 grams or more at any time within three hours after driving, measured from alcohol consumed before driving ended. Because this theory relies on a specific chemical test result, the prosecution does not need to separately prove that the driver was actually impaired or driving less safely. Reaching the threshold is enough on its own to establish the offense. Different, lower thresholds apply in narrower circumstances: drivers operating commercial motor vehicles face a lower per se threshold of 0.04 grams, and drivers under the age of 21 are subject to a still lower threshold of 0.02 grams under Georgia’s separate provision addressing underage drivers.

Less-Safe Theories Beyond Alcohol

The statute also extends the less-safe framework beyond alcohol alone. O.C.G.A. § 40-6-391(a)(2) addresses driving under the influence of any drug to the extent that it is less safe to drive. Subsection (a)(3) covers driving under the intentional influence of glue, aerosol, or other toxic vapors, again under a less-safe standard. Subsection (a)(4) addresses driving under the combined influence of two or more of these substances, alcohol, drugs, or toxic vapors, where the combination makes driving less safe. None of these subsections relies on a fixed chemical threshold; each requires proof that the substance or combination of substances actually impaired the person’s ability to drive safely.

The Per Se Controlled Substance Theory

A separate per se theory exists for certain drugs. Under O.C.G.A. § 40-6-391(a)(6), it is illegal to drive with any amount of marijuana or a controlled substance, as defined elsewhere in Georgia law, present in the blood or urine, including the metabolites and derivatives of those substances, regardless of whether alcohol is also present. Unlike the less-safe drug theory, this provision does not require proof that the substance actually impaired the driver’s ability to operate the vehicle. The presence of a detectable amount, established through chemical testing, is what the theory is built around. The deeper procedural and substantive issues that arise specifically in drug DUI prosecutions, including how detection and metabolite evidence is handled, extend well beyond this basic framework and are addressed elsewhere.

How These Theories Interact

It is common for a single DUI charge or set of charges to be pursued under more than one theory at the same time, particularly where both a chemical test result and other evidence of impairment exist. A driver might be charged under both the less-safe theory and the per se theory based on the same incident, allowing the prosecution to proceed under either theory depending on what the evidence supports at trial. Where a defendant is convicted under more than one theory for what is legally the same underlying act, Georgia’s general merger principles typically apply, meaning the convictions resolve into a single sentence rather than separate, stacked sentences for what amounts to one offense.

Why the Distinction Matters

The practical difference between these theories often comes down to what kind of evidence the prosecution relies on. A per se theory is generally built around a chemical test result, whether from breath, blood, or urine testing. A less-safe theory can be pursued even in the absence of any chemical test, relying instead on the totality of the circumstances surrounding the stop and the driver’s conduct. Recognizing which theory or theories apply to a given charge clarifies what the state is required to prove in that particular case.

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