10 Things to Know About DWI Testing

December 9th, 2019

Posted By

Kevin P. O'Keefe

Contributor: Kevin P. O'Keefe

1. Your driver’s license cannot be administratively suspended for refusing Standardized Field Sobriety Tests (SFST) as it can for refusing a breath or blood test. However, it is important to understand that your consciousness of guilt by refusing any testing is a permissible argument for the prosecution.

2. Only three tests are standardized, that is scientifically studied against a known blood alcohol level in a subject. The Horizontal Gaze Nystagmus (follow the pen), Walk and Turn, and One-Leg Stand are the three standardized field sobriety tests.

3. The newest NHTSA field manual does not require police to use an actual line in the walk the line portion of the Walk and Turn test where prior versions had this requirement.

4. The accuracy of breath testing devices has been called into serious question, most recently in this recent New York Times article: https://www.nytimes.com/2019/11/03/business/drunk-driving-breathalyzer.html

5. Most police departments in New Hampshire do not videotape SFSTs. This practice has been common in many other jurisdictions for years.

6. The Horizontal Gaze Nystagmus test’s accuracy is predicated on mathematical estimations. One of the 3 clues per eye is the onset of nystagmus prior to the officer moving the pen across the subject’s face to create a 45-degree angle. In an effort to achieve the 45-degree angle, the officer holds the pen 12-15 inches from the subject’s face and moves it the same distance horizontally to create an isosceles triangle.

7. You are allowed a 1-inch margin of error between heel and toe during the Walk and Turn test.

8. All of these tests are divided-attention tasks. This means that they simultaneously assess mental and physical functioning.

9. Field sobriety tests are not standardized to assess impairment by drugs alone. Studies have been done in this field, but detecting the type of drug via SFSTs alone is very difficult.

10. A clue will be scored against you if you do not wait heel-to-toe during the instructional phase of the Walk and Turn test. Standing as you would in normal life is strike one against you.