What mistakes do police officers commonly make during DUI investigations?
Answer:
One of the most common mistakes is failing to consider alternative explanations for signs they interpret as impairment. If an officer smells alcohol at a car window, they often presume a DUI immediately, without exploring other possibilities — and that happens to people every day. If you’re in our area, give us a call and we’ll help.
Presuming Impairment the Moment Alcohol Is Detected
The odor of alcohol only tells an officer that alcohol was consumed at some point — it says nothing about how much, when, or whether it actually affected your ability to drive. Treating that smell as confirmation of impairment, rather than one data point among several, is exactly the shortcut that leads officers to skip the rest of the investigation they should be doing.
Treating Bloodshot Eyes as Proof of Drinking
Bloodshot or watery eyes are one of the most commonly cited “clues” in DUI reports, but they’re also one of the weakest. Allergies, fatigue, contact lenses, dry air, and simple exposure to bright headlights or a flashlight can all produce the same look. In fact, NHTSA’s own 1997 research report on detecting impairment specifically eliminated flushed faces and bloodshot eyes as validated cues, precisely because they’re open to subjective interpretation and commonly caused by things that have nothing to do with alcohol.
Reading Nervousness or Fatigue as Slurred Speech
Being pulled over is stressful, and stress affects how people talk. Mumbling, stumbling over words, or speaking too fast or too slow can just as easily come from nerves, exhaustion after a long day, or a preexisting speech pattern as from alcohol. An officer who logs “slurred speech” without considering the obvious alternative explanations is building a weaker observation than the report makes it sound.
Ignoring Physical Conditions During Field Sobriety Tests
The walk-and-turn and one-leg stand tests assume good balance, mobility, and coordination under stress — assumptions that don’t hold for everyone. Inner ear issues, old injuries, age, weight, uneven pavement, and poor footwear can all cause someone to fail these tests without any alcohol involved at all. An officer who doesn’t ask about any of that before scoring the test as “failed” is making a mistake that shows up in nearly every DUI report.
Relying on Memory Instead of the Video
Police reports are often written well after the stop, based on an officer’s recollection rather than a frame-by-frame review of the dashcam or bodycam footage. When the two don’t match — when the video shows steadier movement, clearer speech, or a calmer demeanor than the report describes — that gap is exactly where an investigation’s mistakes become visible.
What to Do Next
If you’re in our area, give us a call and we’ll help.
