These flawed studies indicate that the SFSTs are not 100% reliable. Remember that with DUIs/OVIs, we are dealing with a person’s freedom and their ability to have a valid driver’s license. The HGN is allegedly accurate 77% of the time; The Walk and Turn Test, 68% of the time; and The One Leg Stand Test, 65% of the time. One could conclude that SFST false positives are certain.
The authors of the of the field test studies state that SFSTs do not measure one’s ability to drive. These tests merely correlate to a percentage chance that a person is at or above a .10g/dL BAC. The San Diego study opines that it would be a .08 BAC, but (as discussed above) there are numerous flaws in the study.
Furthermore, the NHTSA student and instructor manuals state that officers MUST follow the precise instructions as set forth for these three SFSTs. In State v. Homan, the Ohio Supreme Court stated:[T]hese tests’ reliability depends largely upon the care with which they are administered. In holding that such testimony [regarding SFST results] is admissible, we stressed the importance of the testing process. We noted that the arresting officer’s knowledge of the test, his training, and his ability to interpret his observations are key considerations in determining admissibility. The small margins of error that characterize field sobriety tests make strict compliance critical. . . . it is well established that in field sobriety testing even minor deviations from the standardized procedures can severely bias the results. . . . we find that strict compliance with standardized field sobriety testing procedures is neither unrealistic nor humanly impossible in the great majority of vehicle stops in which the police choose to administer the tests.
Based on these NHTSA mandates and the Ohio Supreme Court holding in Homan, attorneys from all over the State of Ohio were suppressing SFST results because officers were not administering the test properly or assessing the suspect’s performance properly.
Read more in this series:
Say No No to the Po Po! (Part 1 of 6)
NHTSA Manuals (Part 2 of 6)
The “Reports” or “Studies” (Part 3 of 6)
What Does It All Mean? (Part 4 of 6)
The Ohio Legislature’s Response (Part 5 of 6)
Conclusion (Part 6 of 6)