The National Highway Traffic Safety Administration (NHTSA) defines standardized field sobriety tests(SFSTs) as follows: “There are three SFST’s, namely Horizontal Gaze Nystagmus (HGN), Walk and Turn, and One Leg Stand. Based on a series of controlled laboratory studies, scientifically validated clues of alcohol impairment have been identified for each of these three tests. They are the only standardized field sobriety tests for which validated clues have been identified.“
Horizontal Gaze and Nystagmus (HGN) is an involuntary jerking of the eyes, occurring as the eyes gaze to the side. According to NHTSA, the Walk and Turn and the One Leg Stand test are “divided attention field sobriety tests.” NHTSA defines a divided attention test as, “a test which requires the subject to concentrate on both mental and physical tasks at the same time.”
A standardized test is a test in which the procedures, apparatus, and scoring have been fixed so that precisely the same testing can be done at different times and at different places. According to NHTSA,validated means, “a document demonstrating that a procedure, process, and/or activity will consistently lead to accurate and reliable results.” However, in the proper context of what the SFSTs are designed to do, validated means, “the correlation between performance on a SFST and a designated blood alcohol concentration (BAC)”.
In 1998, the article “Validation of the Standardized Field Sobriety Test Battery at BACs Below 0.10%: Final Report” was submitted to NHTSA. The article stated as follows: “Horizontal Gaze and Nystagmus lacks face validity because it does not appear to be linked to the requirements of driving a motor vehicle. The reasoning is correct, but it is based on the incorrect assumption that Field Sobriety Tests are designed to measure driving impairment.”
The authors of that report went on to state, “driving a motor vehicle is a very complex activity that involves a wide variety of tasks and operator capabilities. It is unlikely that complex human performance, such as that required to safely drive an automobile, can be measured at roadside.”
If that is the position that was forwarded to NHTSA, then why in the world are police officers actually administering these tests?
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)