Field Sobriety Tests
Many people are familiar with the sight of a police officer administering sobriety tests to a driver on the side of the road. These tests and others make up the Standardized Field Sobriety Test (SFST) that is used by police departments throughout the country. The goal of these tests is to determine if a driver should be placed under arrest for suspicion of driving while intoxicated.
Types of DWI Field Tests
There are three main tests that comprise the SFST. Each test allows the officer to observe the behavior of the driver to check for signs of impairment. These tests were developed and put into use in the 1970’s by the National Highway Safety Administration to help police officers perform their duties more effectively.
- The One Leg Stand: Just as the name implies, the officer asks the driver to stand on one leg while raising the other leg six inches off of the ground and counting to a certain number. Alcohol consumption affects a person’s sense of balance and coordination so a driver who has trouble with this test may be impaired.
- The Walk and Turn: The officer asks the driver to try to walk a straight line, turn around and then walk back while counting aloud. Trouble performing these tasks simultaneously may indicate intoxication.
- The Horizontal Nystagmus Test: The final test is the Horizontal Nystagmus, or HGN test. Nystagmus is a term that refers to the natural involuntary movement of the human eyes. Alcohol consumption can cause the eyes to have an exaggerated nystagmus. The officer may ask the driver to follow the movement of a flashlight with his or her eyes. This allows the officer to check for excess movement or wobbling of the driver’s eyes.
These tests have been criticized for being difficult to perform even by sober drivers. For example, a driver with a physical disability may have trouble standing on one leg even if they have not been drinking. As a result, these tests are often used to determine if the officer should administer a breath or blood test to a driver suspected of impairment.