Law Office of Ronald A. Cabanayan
Law Office of
Ronald A. Cabanayan

DUI ~ Criminal Defense ~ Immigration/Naturalization

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How do field sobriety tests work?

On Behalf of | Dec 16, 2022 | DUI Defense

As you know, police will perform a traffic stop if they have reasonable suspicion that a driver is drunk. In most cases, but not all, the officer will ask the driver to take a breath test. A breath test – a small, hand-sized machine that greatly resembles a radio – evaluates the blood-alcohol content (BAC) in a person’s breath, which, exceeding the driving limit of 0.08% BAC, can result in a DUI charge on the driver’s record.

While a breath test can often give an accurate result of a driver’s inebriation level, police officers may ask the driver to perform a standardized field sobriety test (SFST). Essentially, an SFST allows the officer to collect more evidence on a suspected drunk driver and even arrest a driver for failing the tests.

What kind of field sobriety tests do officers use? Here’s what you should know:

3 kinds of SFSTs

While police may use non-standardized field sobriety tests that they believe would give them a clear evaluation of a suspected drunk driver, which may include listing the alphabet backward or doing a dance, there are three typical SFSTs. The following are commonly used SFSTs:

  • Horizontal gaze test: The suspect is asked to look at a single spot without moving their head or allowing their eyes to flicker or drift off the spot.
  • Walk-and-turn test: The suspect is asked to walk in a straight line, turn, and walk back to where they started without deviating off the line.
  • One-legged stand test: The suspect is asked to stand on one leg without falling.

If the suspect fails the test, as stated above, then they could be arrested or asked to take a breathalyzer test to collect more evidence.

Declining an SFST

While these tests may seem accurate since they are part of an officer’s training, the truth to the matter is that they are subjective. In other words, these tests can be highly inaccurate.

Why would an SFST be inaccurate? First, an officer may not notice signs that a driver is drunk. Second, a drunk driver may have a high tolerance to the effects of alcohol. Last, a person with disabilities may fail these tests because of a physical or mental condition.

As a result, many people have to seek legal help to reduce their charges or have a DUI expunged from their records.