How do police determine whether someone is impaired by drugs instead of alcohol?

Answer:
When an officer suspects impairment but doesn’t suspect alcohol, they often ask — or gently steer a driver toward — standardized field sobriety tests. In the officer’s view, these tests help determine whether someone is impaired due to a prescription medication or other drug. If you’ve performed these tests and were subsequently charged with a DUI, give us a call and let us help.

Field Sobriety Tests as the First Screening Tool

Without the odor of alcohol to point to, officers rely on the same standardized field sobriety tests used in alcohol cases as a general impairment screen. Certain results, like a particular pattern of eye movement during the horizontal gaze nystagmus test, can suggest impairment from a category of drugs even when there’s no breath alcohol result to explain what’s going on.

When FSTs Point to Drugs, Officers Often Call in a Drug Recognition Expert

If field sobriety tests suggest impairment that a breath test can’t explain, many departments bring in an officer with additional training: a Drug Recognition Expert, or DRE. This program, developed through the International Association of Chiefs of Police with NHTSA support, trains officers in a more detailed protocol specifically aimed at figuring out whether drugs are involved and which kind.

The 12-Step DRE Evaluation

The DRE protocol is a standardized 12-step process that includes reviewing the breath alcohol result, interviewing the arresting officer, conducting eye examinations, checking vital signs, examining muscle tone, and looking for injection sites, among other steps, before the officer forms an opinion on impairment and drug category. It’s a far more involved evaluation than the roadside field sobriety tests most people are familiar with.

The Seven Drug Categories DREs Are Trained to Identify

DREs are trained to classify impairment into one of seven categories: central nervous system depressants, central nervous system stimulants, hallucinogens, PCP, narcotic analgesics, inhalants, and cannabis. To become certified, an officer has to correctly identify the drug category in a set percentage of supervised evaluations, verified afterward by toxicology results.

Why DRE Conclusions Are Contested

The reliability of DRE evaluations is genuinely disputed. NHTSA-funded studies report high accuracy rates, but independent research has found meaningfully lower correct-classification rates depending on the drug category. Cannabis is a particular problem area, since there’s no established relationship between THC levels in blood and actual functional impairment the way there is for alcohol and BAC. Georgia courts generally allow DRE testimony as expert opinion, but that doesn’t mean it goes unchallenged — the officer’s training, certification, and the specific observations behind the conclusion are all fair game.

What to Do Next

If you’ve performed these tests and were subsequently charged with a DUI, give us a call and let us help.

5 Star Rating

Brett and his team were beyond supportive, helpful, gracious, caring and knowledgeable! We went through the most challenging and difficult time in our life and he was there every step of the way. With results we could never have imagined but definitely prayed for.

Not to mention his level of professionalism. From the first time we spoke to the first time we saw him in court. He stood out from almost every other attorney there. We were so appreciative that our attorney looked and was so professional, pulled together and prepared. When so many others were none of these things.

Thank you just doesn’t seem like enough to convey our feelings and appreciation.

Karen L.

5 Star Rating

I tried to write this several times and it brought me to tears. First may I say this has been the hardest three years of my life. Five lawyers I interviewed and none even understood the law as it applied to my case. So I thought I would try one more and it was Brett. From our first conversation together I knew he understood the law and was the perfect one for the case. I want to say how he prepared the case and presented it, achieving a full dismissal and ruling the police violated my first amendment rights. Complete genius!!!!

If you're reading this review and unsure, stop...call Brett. He always returned my call or texts within a couple hours, never more than 24 hours. He was always courteous and knowledgeable, trust me he talked me off the ledge a couple times. I would have given him 10 stars but 5 was the only option. Thank you Brett for all you did for me!!!!!