Most people are familiar with the concept of field sobriety tests from movies and television. However, the reality may be a little different than those fictional depictions.
While there is a wide range of possible field sobriety tests, only a few comprise the battery of the Standardized Field Sobriety Test. Law enforcement may be more likely to perform these assessments as part of the standardized test when pulling over a driver for possible DUI or OWI.
What is the Standardized Field Sobriety Test?
The Standardized Field Sobriety Test consists of three assessments that have undergone testing to prove their effectiveness. Testing under laboratory and field conditions has shown these assessments to be the most consistent at correctly identifying drivers who are under the influence.
According to AAA, three different assessments collectively make up the Standardized Field Sobriety Test:
- One-leg stand test
- Walk-and-turn test
- Horizontal gaze nystagmus test
The first two tests are more or less what they sound like, and the purpose is to look for loss of balance and other indicators of intoxication. The horizontal gaze nystagmus test involves asking the driver to follow the motion of a finger or other object with his or her eyes. The purpose is to look for an involuntary twitching of the eyeballs that may be more pronounced when intoxicated.
Do authorities have to use the SFST?
There is no requirement for law enforcement to administer the SFST. Authorities can administer any field sobriety tests that they want. However, using non-standardized assessments may affect the admissibility of the results in court.
How effective is the SFST?
According to Atlas Obscura, the individual assessments are less effective than one might assume, with the one-leg stand test being 65% effective and the walk-and-turn assessment only a little better at 68%. The horizontal gaze nystagmus test is the most effective of the three at 77%.
However, when performed together, the assessments that comprise the SFST become even more effective, correctly identifying alcohol-impaired drivers over 90% of the time. In other words, the SFST, on the whole, is more effective than any one of its components.