Many officers have asked me why it is necessary to follow the procedures outlined in the NHTSA manual when performing the standardized field sobriety tests. There are several reasons why officers must follow the standardized procedures. I will outline those reasons in this article.
First, the scientific reliability of the three standardized tests are based on the research behind the procedures used to administer the tests. The three tests were validated through research in the 1970’s by the Southern California Research Institute funded by NHTSA. According to the NHTSA manual, the term validated means that “a documented act of demonstrating a procedure, process, and/or activity will consistently lead to accurate and reliable results.” As long as officers follow the procedures as outlined, the results will be reliable.
Next, the court system in Texas has laid out why officers should follow the procedures. In the case of Emerson v. State, 880 S.W.2d 759 (1994), the Court of Criminal Appeals stated that “to be considered reliable, evidence based on a scientific theory must satisfy three criteria: 1) the underlying scientific theory must be valid; 2) the technique applying the theory must be valid; and 3) the technique must have been applied properly on the occasion in question.” The Court took judicial notice that horizontal gaze nystagmus meets those three criteria if administered properly.
The court went on to say, “when administering the HGN test, those officers must follow standardized procedures as outlined in the DWI Detection manual published by NHTSA.” This includes doing the medical checks before administering HGN. The Court stated, “the manual require an officer to screen for factors other than alcohol that potentially contribute to, or cause, nystagmus, such as other drugs, neurological disorders, and brain damage, prior to administering the HGN test.” This is a reminder for officers to follow the steps outlined in the NHTSA manual.
The Court continued by emphasizing that the officer must show they are qualified to testify in court. To do this, the Court said that the witness testifying must be “qualified as an expert on the HGN test, specifically concerning its administration and technique. In the case of a police officer or other law enforcement official, this requirement will be satisfied by proof that the officer has received practitioner certification by the State of Texas to administer the HGN.” The Court concluded by saying to receive practitioner certification in Texas, the officer must attend and successfully pass the 24-hour NHTSA approved class on standardized field sobriety testing.
Lastly, the NHTSA manual states that the tests must be done in the standardized format. In session 8, page 10 of the 2018 DWI Detection and Standardized Field Sobriety Testing manual, NHTSA states the “three standardized tests were found to be highly reliable in identifying subjects whose BACs were at or above 0.10. The results of the study unmistakably validated the SFSTs. The ‘Standardized’ elements included standardized administrative procedures, standardized clues and standardized criteria.” Part of the standardization includes performing the three tests in a standard order. The order is HGN first, walk and turn second and one leg stand third. This was emphasized in session 9, page 4, during the test battery demonstrations.
For officers to be able to testify in court about the three standardized tests, especially HGN, the officer must show they were properly trained, know how to administer the tests, and know how to evaluate the suspect’s performance. The best way to do this is to follow all the standardized procedures outlined in the NHTSA manual.
This article was written by Kevin Ryan. He is the Lead Instructor for the Texas SFST Program. He has been a certified peace officer since 1977. He has been an SFST Instructor since 1991 and has conducted over 75 SFST Practitioner courses and eight SFST Instructor courses.