If a person is pulled over on suspicion of driving while intoxicated (DWI) in the state of Texas, there is a good chance that they will be asked to take field sobriety tests. These tests will involve certain types of physical tasks that are meant to help determine a driver's level of impairment and whether they have been drinking alcohol or have used other substances that have affected their ability to operate a vehicle safely. It is important to understand the role that field sobriety tests will play in a DWI case, including their purpose, their validity, and when they can be refused.
Understanding Field Sobriety Tests
When a police officer pulls a driver over because they believe the person may be intoxicated, they will observe the person and look for a reason to perform an arrest. To establish probable cause, or a strong belief that a person has violated the law, the officer may ask the driver to submit to field sobriety tests. These tests are designed to measure an individual’s physical coordination and their ability to follow instructions.
There are three types of standard field sobriety tests (SFSTs) that have been approved by the National Highway Traffic Safety Administration (NHTSA). The horizontal gaze nystagmus (HGN) test will involve an officer asking a person to follow an object with their eyes as they look for involuntary movements. In the walk-and-turn test, a driver will be asked to take several heel-to-toe steps in a straight line, turn around, and walk back to their original position. The officer will be watching to see if the person loses their balance or is unable to follow directions correctly. The one-leg stand test will require a person to stand with one foot raised off the ground for 30 seconds, and if they lose their balance or put their foot down, this may be seen as an indication that they are intoxicated.
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