What Most People Get Wrong About Field Sobriety Tests (And Why It Matters)
“I think I passed the tests.”
It’s one of the most common things I hear from people after a DUI arrest. They’re referring to the roadside field sobriety tests. Standing on one leg, walking heel-to-toe, following a pen with their eyes. And they often feel like they did just fine.
But here’s the truth:
Standardized Field Sobriety Tests (SFSTs) are not pass/fail. They’re scored based on specific “clues” and those clues can be missed, misinterpreted, or improperly documented.
How the Tests Actually Work
Officers are trained to look for validated indicators of impairment. For example:
The Horizontal Gaze Nystagmus (HGN) test checks for involuntary jerking of the eyes as they move side-to-side, which can indicate impairment of alcohol and other CNS Depressants (and a few other things, but we won’t get into that here).
The Walk and Turn (WAT) looks for balance, coordination, and ability to divide attention.
The One Leg Stand (OLS) similar to the WAT, is also a divided attention test.
Each test has a set number of possible clues. You don’t need to “fail” the whole test, just displaying a few clues (especially during HGN) is often enough for officers to form probable cause for arrest.
But here's the problem: Most people, and many officers, misunderstand how these tests are supposed to work.
Where Things Go Wrong
Despite being “standardized,” the tests are often administered:
In poor lighting or uneven terrain
With vague or incorrect instructions
Without a proper medical rule-out
While ignoring environmental factors (cold, nerves, fatigue)
Even worse, many reports simply state that the subject “performed poorly,” without detailing what clues were actually observed or whether the tests were conducted correctly at all.
As a former Drug Recognition Expert (DRE) and law enforcement officer, I’ve seen both sides. I’ve administered these tests, and now I break down the way they’re conducted in case after case.
Why This Matters for Your Case
If these tests weren’t done correctly, the evidence they generate may not be valid, and that could change everything from negotiation leverage to trial strategy.
That’s exactly what I look for.
When I review discovery, I don’t just glance at the report and move on. I go frame-by-frame through the video, cross-check it against the NHTSA SFST manual, and break down what happened versus what was documented.
You Deserve More Than Assumptions
SFSTs are powerful tools, and they truly are NOT set up “for people to fail”, but only when used correctly. A misstep by the officer can become a major point of challenge in your defense. But only if someone knows how to find it.
That’s what I do.
