Horizontal Gaze Nystagmus Tests

These simple tests are only to give an officer just cause – called ‘probable cause’ – to arrest the driver on suspicion of DUI. On average, these tests range from 65-80 percent reliable in establishing that a driver is in fact under the influence of drugs or alcohol.

If a driver is pulled over on a routine stop and the police officer suspects intoxication, field sobriety tests may be conducted. The driver must perform simple physical or cognitive tests to determine sobriety. In 1982, the National Highway Traffic and Safety Administration (NHTSA) guidelines were created to help make these tests more accurate. They are now called ‘standardized field sobriety tests.’

The tests are the:

- one-leg stand
- walk-and-turn
- horizontal gaze nystagmus test.

The ‘horizontal gaze nystagmus test’ (HGN) is relatively new to field sobriety tests and is fairly accurate if administered properly.

Police officers are trained by the NHTSA in conducting these tests to increase their accuracy.