A drug recognition expert exam is a standardized evaluation that a specially trained California officer performs on a driver suspected of drug impairment, to help decide whether the driver is impaired and which drug category may be involved. It supports a DUI charge under Vehicle Code 23152(f) or 23152(g), alongside field sobriety tests and chemical test results.
Who is a drug recognition expert, and who calls one?
A drug recognition expert is a law enforcement officer trained and certified through California's Drug Evaluation and Classification Program, usually involved after signs of drug impairment appear.
The California Highway Patrol is the state coordinator of the Drug Evaluation and Classification Program (DECP), which trains officers as Drug Recognition Experts, also called Drug Recognition Evaluators in the program's own materials, both abbreviated DRE. The same program coordinates related courses: Advanced Roadside Impaired Driving Enforcement (ARIDE), Standardized Field Sobriety Testing (SFST), and a Drug Impairment Training for Educational Professionals (DITEP) course for educators. Certification has two required parts, a 72-hour classroom course and a separate 32-hour field certification course, and both must be completed before an officer can certify as a DRE. An officer typically calls a Drug Recognition Expert when a stop or arrest suggests impairment that a breath alcohol test alone does not fully explain, since Vehicle Code 23152(f) and 23152(g) cover driving under the influence of a drug, or of alcohol and a drug together, and neither subdivision sets a numeric blood or breath limit the way subdivision (b) does for alcohol.
What happens during a drug recognition evaluation?
The CHP's drug category symptomology matrix lists the major indicators checked: nystagmus and convergence of the eyes, pupil size and light reaction, pulse, blood pressure, temperature and muscle tone.
That matrix, one of the DRE references on the CHP's program forms page, sets out the expected signs for each of seven drug categories: horizontal and vertical gaze nystagmus (a fluttering of the eyes), lack of convergence, pupil size and reaction to light, pulse rate, blood pressure, body temperature and muscle tone, plus general signs such as droopy eyelids and puncture or track marks. It gives normal ranges for pupil size in room light, near total darkness and direct light, and it warns that the signs can vary with individual reaction, the dose taken and drug interactions. Read against the matrix, the signs point toward a drug category, which the officer's opinion can name. Separately, Vehicle Code 23612 treats a driver lawfully arrested for DUI as consenting to a blood test for drugs, or a urine test if blood is unavailable.
Caption: Indicators on the CHP's drug category symptomology matrix.
| Indicator | What the matrix lists by drug category |
|---|---|
| Horizontal and vertical gaze nystagmus | Present or none |
| Lack of convergence | Present or none |
| Pupil size | Normal, dilated or constricted |
| Reaction to light | Slow, normal, or little or none visible |
| Pulse, blood pressure, body temperature | Up, down or normal |
| Muscle tone | Flaccid, rigid or normal |
| General indicators | Signs such as droopy eyelids, puncture or track marks, and odors |
A published California Court of Appeal decision illustrates the kind of findings this evaluation can record. In that case, the evaluating officer measured the driver's heart rate, checked pupil size in normal room light, in near darkness and with a pen light, and examined the mouth and arms for other physical signs during the exam (People v. Jimenez, Cal. Ct. App., 5th Dist., Dec. 11, 2015, No. F067846, certified for partial publication).
What does the officer record, and how is it used in a DUI case?
The officer documents each part of the exam on a standard department form, and that record, together with any toxicology results, can become evidence in the DUI case.
The California Highway Patrol's Drug Recognition Evaluator program uses its own standard form, CHP 202 DRE, to record a certified officer's observations during an evaluation. The officer's recorded observations, opinion about the drug category involved, and any toxicology results can all become evidence the prosecution offers to prove a Vehicle Code 23152(f) or 23152(g) charge, since neither subdivision sets a numeric blood or breath limit. A valid prescription for the drug involved is not a defense to the charge; Vehicle Code 23630 states that being entitled to use a drug under California law "shall not constitute a defense" to a drug DUI. The firm's separate explainer on choosing a breath or blood test after a DUI arrest covers how that earlier chemical test choice works, including when officers can require a blood sample in a suspected drug case.
How does a defense lawyer test a drug recognition evaluation?
A lawyer can question the training and conclusions behind each part of the exam, since the evaluation rests on an officer's trained opinion rather than a single numeric test.
Because Vehicle Code 23152(f) and 23152(g) set no blood or breath number for drugs, the prosecution's case leans heavily on the evaluating officer's training, observations, and opinion rather than on one measurement the way a 0.08 percent breath result does under subdivision (b). A defense lawyer can examine the officer's DRE certification and recertification history, whether each recorded sign fits the matrix's indicators for the drug category named, whether the toxicology result supports or contradicts that category, and whether the signs could have another medical or physical explanation; the matrix itself warns that signs can vary with individual reaction, dose and drug interactions. None of this means a drug DUI case cannot be proven; it means the evaluation itself, like any other evidence, can be reviewed and challenged.
How does this evaluation connect to a drug DUI charge?
A drug recognition evaluation is evidence inside a Vehicle Code 23152(f) or 23152(g) case, not a separate charge on its own.
The evaluation itself is not a charge. It supports the separate offense of driving under the influence of a drug, or of alcohol and a drug together, which the firm's overview of drug DUI charges discusses in more detail, including how those cases differ from an alcohol-only DUI. A Drug Recognition Expert is usually involved after a driver has already gone through roadside field sobriety tests, which are a separate, earlier part of many DUI stops.
Frequently asked questions
Is a Drug Recognition Expert a medical doctor?
No. A DRE is a law enforcement officer who has completed specialized training through California's Drug Evaluation and Classification Program. The role is a trained law enforcement certification, not a medical credential.
Does refusing a chemical test affect a drug DUI case?
Yes. Vehicle Code 23612 sets out the implied consent rules for blood, breath, and urine testing, and a refusal carries its own license and criminal consequences, separate from the drug recognition evaluation itself.
Does a low or 0.00 percent alcohol result end a drug DUI investigation?
No. Vehicle Code 23152(f) and 23152(g) do not depend on blood alcohol content. A low or 0.00 percent alcohol result is actually one of the reasons an officer may request a drug recognition evaluation in the first place; see DUI With BAC Under 0.08 in California for how an alcohol DUI can stand on similar reasoning.
How many drug categories does the training cover?
California's Drug Evaluation and Classification Program curriculum addresses what the California Highway Patrol's own course materials describe as "the seven major drug categories," covered in both the ARIDE and DRE coursework.
Is a Drug Recognition Expert's opinion the only evidence in a drug DUI case?
No. A drug DUI case can also include the arresting officer's own observations, field sobriety test performance, and laboratory toxicology results, in addition to the Drug Recognition Expert's evaluation and opinion.
Does California's drug recognition program only train officers for DUI stops?
No. The same state program also coordinates related training, including a drug impairment course for educators (DITEP) and a bridge course for officers who are not yet full DREs (ARIDE), in addition to full Drug Recognition Expert certification.
Talk to a lawyer
If you are facing a drug DUI charge under Vehicle Code 23152(f) or 23152(g), the Law Offices of David S. Chesley offers a free, confidential consultation, is available 24/7, and discusses fees and payment plans before you agree to representation. Se habla español. Call (800) 755-5174 or use the contact page to talk through the evaluation and the evidence in your case.