When law enforcement suspects that a driver is impaired by drugs rather than — or in addition to — alcohol, they may call upon a specially trained officer known as a Drug Recognition Expert (DRE), sometimes also called a Drug Recognition Evaluator. DREs occupy a unique and sometimes controversial role in DUI investigations, claiming the ability to identify not only that a driver is impaired, but specifically which category or categories of drugs are responsible for that impairment. Understanding what a DRE actually is, how they are trained, and where their evaluations fall short is essential for anyone facing a DUI-drugs charge in Georgia.

What Is a Drug Recognition Expert?

A Drug Recognition Expert is a law enforcement officer — typically a patrol officer or investigator — who has received advanced training in the detection of drug-induced impairment beyond the standard NHTSA field sobriety test curriculum that most officers receive at the police academy. DRE training is not provided through Georgia’s Peace Officer Standards and Training (POST) Council as part of basic officer certification. Instead, it is provided through the International Association of Chiefs of Police (IACP) Drug Evaluation and Classification (DEC) Program, which operates in partnership with NHTSA.

The DRE certification program consists of three phases: a 16-hour pre-school covering basic drug knowledge; a 56-hour classroom training covering the 12-step DRE evaluation protocol, pharmacology, and physiology; and a field certification phase requiring the officer to conduct a minimum of 12 evaluations on subjects who are subsequently confirmed through toxicology to be impaired by drugs. This is a substantial training commitment, and DRE-certified officers are far less common in local law enforcement than standard patrol officers.

The 12-Step DRE Evaluation Protocol

The DRE evaluation is a structured, 12-step examination that is intended to be comprehensive and systematic. When an officer trained as a DRE conducts an evaluation, they will administer the following steps:

• Breath alcohol test — to determine the subject’s current BAC and rule out alcohol as the sole cause of observed impairment
• Interview of arresting officer — to obtain information about the subject’s driving behavior and initial contact
• Preliminary examination — including questions about medical conditions, medications, and recent drug use, along with observation of the subject’s eyes and general appearance
• Eye examinations — including horizontal gaze nystagmus (HGN), vertical gaze nystagmus (VGN), and lack of convergence
• Divided attention psychophysical tests — including the Romberg balance test, walk-and-turn test, one-leg stand test, and finger-to-nose test
• Vital signs examination — pulse rate, blood pressure, and body temperature
• Dark room examinations — pupil size measurements under three lighting conditions: near total darkness, indirect ambient light, and direct light
• Examination of muscle tone — to detect the rigidity or flaccidity associated with certain drug categories
• Examination for injection sites — to identify evidence of intravenous or subcutaneous drug use
• Subject’s statements and other observations — including any admissions regarding drug use
• DRE’s opinion — a formal opinion as to whether the subject is impaired, and if so, which of the seven drug categories is responsible
• Toxicological examination — collection of a urine or blood sample to provide independent chemical confirmation

The Seven Drug Categories

DREs are trained to identify impairment within one or more of seven recognized drug categories, each of which produces a distinct physiological profile that is theoretically detectable through the 12-step evaluation. These categories are: central nervous system (CNS) depressants; CNS stimulants; hallucinogens; dissociative anesthetics; narcotic analgesics; inhalants; and cannabis.

Each category is associated with expected ranges for vital signs (pulse, blood pressure, temperature), pupil size under different lighting conditions, and muscle tone. The DRE forms an opinion about which category or categories are present based on whether the subject’s profile matches the expected presentation for each drug type. This analysis is what DREs testify to in court.

How Reliable Are DRE Evaluations?

The reliability of DRE evaluations is one of the most contested issues in DUI-drugs litigation. Proponents of the DRE program point to studies — many conducted or funded by NHTSA or IACP — that report accuracy rates for DRE opinions in the range of 85 to 95 percent in laboratory or controlled settings. However, independent researchers and defense experts have raised substantial criticisms of these findings.

First, the studies supporting DRE reliability often use toxicological confirmation as the benchmark for accuracy, but the presence of a drug in the blood or urine does not establish that the person was actually impaired at the time of driving. Many drugs, particularly cannabis, are detectable in blood and urine long after their impairing effects have worn off. A DRE who identifies cannabis impairment based on a physiological profile, confirmed by a positive urine test, may have correctly identified recent cannabis use without correctly identifying current impairment.

Second, the DRE evaluation relies heavily on the officer’s subjective interpretation of observations such as muscle tone and pupil size. These measurements, while nominally objective, are subject to significant observer variation. Pupil size, in particular, is affected by lighting conditions, individual baseline variation, and prescription medications — none of which are drug-induced impairment.

Third, the DRE evaluation was developed and validated primarily for use in alcohol and narcotic impairment cases. Its extension to cannabis impairment — the most common drug category encountered in modern DUI-drugs cases — involves significant scientific controversy, as there is no established correlation between blood or urine THC levels and functional impairment analogous to the well-established relationship between BAC and impairment.

Challenging DRE Evidence in Georgia Courts

Georgia courts have generally admitted DRE opinion testimony under the framework established for expert witnesses, subject to foundation requirements regarding the officer’s training and certification. However, the admission of DRE testimony does not preclude vigorous cross-examination or the presentation of competing expert testimony.

Defense attorneys challenging DRE evidence in Georgia typically attack: the completeness of the officer’s DRE certification; deviations from the 12-step protocol; the absence or inadequacy of toxicological confirmation; the scientific debate surrounding DRE reliability in the specific drug category at issue; and the difference between detected drug presence and demonstrated impairment. In cases where the DRE’s opinion is based primarily on cannabis impairment, the absence of a per se legal limit and the scientific uncertainty about THC impairment provide additional grounds for challenge.

An independent toxicologist or pharmacologist can serve as a powerful defense expert in DUI-drugs cases, helping the jury understand the gap between chemical detection and actual impairment and scrutinizing the DRE’s methodology and conclusions. Given the increasing prevalence of DUI-drugs charges in Georgia, and the significant penalties they carry under O.C.G.A. § 40-6-391, these challenges are an important component of a comprehensive defense strategy.