SFST REVIEW

Evaluating whether standardized field sobriety tests were administered and interpreted correctly.

STANDARDIZED FIELD SOBRIETY TESTING

Standardized field sobriety tests are standardized for a reason. The instructions, demonstrations, administration, and interpretation of each test are designed to be performed in a specific manner.

I review SFST administration against NHTSA training and the available video evidence to identify deviations, determine their significance, and evaluate whether the officer's conclusions are supported by what actually occurred.

HORIZONTAL GAZE NYSTAGMUS (HGN)

HGN is often treated as the most technical of the standardized field sobriety tests. Proper administration requires specific positioning, stimulus movement, timing, sequencing, and observation of the eyes.

I review the complete HGN administration to determine whether required procedures were followed, whether the officer's claimed clues are supported by the video, and whether deviations affect the reliability of the officer's interpretation.

WALK-AND-TURN

The Walk-and-Turn is a divided-attention test that requires specific instructions, a standardized demonstration, and observation of eight validated clues.

I review the officer's instructions and demonstration, the testing surface and conditions, the subject's performance, and the officer's interpretation of each claimed clue. Video evidence can be particularly important when comparing what occurred with what was ultimately documented.

ONE-LEG STAND

The One-Leg Stand is a divided-attention test requiring standardized instructions, demonstration, timing, and observation of four validated clues.

I review the officer's administration of the test, the conditions under which it was performed, the subject's performance, and whether the officer's interpretation is consistent with NHTSA training and the available video evidence.

WHAT I LOOK FOR

My review goes beyond counting clues. I evaluate whether the tests were properly instructed, demonstrated, administered, and interpreted, and whether the officer’s conclusions are supported by the actual evidence.

Small deviations do not automatically invalidate an SFST. The question is what occurred, why it matters, and how it affects the reliability and weight of the officer’s conclusions.