The police may perform a traffic stop if they suspect a driver is drunk. The police may have reasonable suspicion that a driver is drunk if the vehicle was swerving between lanes, driving at inconsistent speeds or the driver was seen leaving a bar. However, the police may need additional evidence to charge them with drunk driving.
A driver may have probable cause of drunk driving if the police see an open bottle of alcohol with them, but this doesn’t happen often. The police could also ask the driver to take a breath test, which could give the police more evidence. Or, the police may ask the driver to perform a standardized field sobriety test (SFST).
An SFST is a physical examination of the driver’s condition. There are three kinds of SFSTs:
Horizontal gaze nystagmus test
A driver who is asked to do a horizontal gaze nystagmus test may need to focus their attention on a single point, such as the officer’s finger or a pen. The officer will then move the object left and right. The driver must keep their head still while they follow the object with their eyes. The police may be looking for loss of focus or eye flickering.
Walk-and-turn test
A walk-and-turn test begins by having the driver stand on a line. The driver will then need to take several steps toe-to-heal. After the stated number of steps, the driver will walk back to where they started while staying on the line. If the driver falls or stumbles, then the police may believe the driver is drunk.
One-legged stand test
The police may ask the driver to do a one-legged stand test. The driver will have to lift one leg up slightly off the ground until the officer tells them to put it down. If the driver uses their hands for balance or falls, then they could be inebriated.
SFSTs are not always accurate and many people fail them because of causes unrelated to alcohol, such as disabilities. People who believe their rights were violated during a traffic stop may need to learn about their legal options.