Field Sobriety Test

Field sobriety tests, used by police officers throughout the United States, are one of the most controversial methods of detecting intoxicated drivers. Standardized testing and training techniques have been developed by the National Highway Traffic Safety Administration (NHTSA) to increase the validity of the tests and standardize the testing process. It is estimated that many sober drivers, especially those with medical conditions, the overweight or the elderly may have difficulty performing field sobriety tests, even when sober.

Field sobriety tests are called divided attention tests and are used to test the ability of a driver to multitask, a skill that is needed to drive safely. Standardized field sobriety tests (SFSTs), which have been adopted by most law enforcement agencies, include the horizontal gaze nystagmus test which tests the eye movement of a driver's eye, the one-leg-stand test and the walk-and-turn test. The one-leg-stand test and the walk-and-turn test will evaluate a driver's ability to follow directions, complete a series of steps and balance (tasks which are difficult to complete if a driver is intoxicated).

Field sobriety tests are not used to determine the blood alcohol concentration of the driver but rather the driver's level of impairment. Officers may also use various handheld breathing devices such as the preliminary alcohol screening (PAS) or preliminary breath test (PBT) along with the other field sobriety tests to gather evidence to determine probable cause for a DUI or drunk driving arrest.