Field Sobriety Tests
2004 NHTSA SFST Refresher Instructor Manual
NHTSA · 2004 · 2.0 MB
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Published in 2004, 2004 NHTSA SFST Refresher Instructor Manual is a NHTSA's instructor guide — the manual an officer's trainers teach from. It documents the exact standardized procedure for HGN, Walk-and-Turn, and One-Leg Stand — and the documented accuracy limits behind calling those tests 'validated'. Because it is the government's own source material, it sets the standard a DUI case can be measured against — not a standard the defense invented.
What this document establishes
It sets out the exact standardized procedure for HGN, Walk-and-Turn, and One-Leg Stand — and the documented accuracy limits behind calling those tests 'validated'. As primary-source material, it lets you compare what actually happened in a case against the written standard, rather than relying on how the procedure is described in court.
How it's used in a DUI defense
The SFST manuals are read line by line against the officer's report and video: the tests are validated only when administered in the prescribed, standardized manner, so a changed instruction, a mistimed HGN pass, an unlisted clue, a skipped demonstration, or a test run on a slope undercuts the very validity the state relies on. The validation studies are where the word 'validated' — and its limits — come from: small samples, near-laboratory conditions, and error rates that misclassify a meaningful share of sober subjects.
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