DUI Investigation: Field Sobriety Tests - California DUI Law and Legal Information

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  6.  » Field Sobriety Tests
  7.  » Standardized FST
  8.  » Horizontal Gaze Nystagmus
  9.  » Walk and Turn Test
  10.  » One-Leg Stand Test
  11.  » Non-Standardized FST
  12.  » Rhomberg Balance Test
  13.  » Finger-to-Nose Test
  14.  » Finger Tap Test
  15.  » Hand Pat Test
  16.  » ABC's Test
  17.  » Numbers Backward Test
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California drivers arrested on suspicion of Driving Under the Influence (DUI), or Driving While Intoxicated (DWI) take a field sobriety test, then worry later that a poor performance means an automatic conviction. However, field sobriety testing is vitally important for both the defense and prosecution in a California DUI case. Prosecutors will attempt to show that any variation between the manner in which police officer explained and demonstrated the tests, and the manner in which the subject performed the tests, is proof of mental or physical impairment. Conversely, criminal defense lawyer with experience defending DUI offenses will use the same results to highlight the absence of mental or physical impairment.

Field sobriety testing have been the subject of much research and study. There are three tests that have been “validated” by the National Highway Traffic Safety Administration (NHTSA). These are the Horizontal Gaze Nystagmus test, the Walk and Turn test, and the One-Leg Stand test. Each of these three tests has precise instructions to be followed in the administration of the test, and precise scoring to be used during the performance phase.

There are also a number of non-standardized tests to show mental or physical impairment. These tests include the Rhomberg Balance test, the Finger-to-Nose test, reciting the alphabet, or ABCs test, the Hand-Pat test, the Finger-Tap test, and other tests as simple as dropping coins in the roadway and asking the subject to pick up those coins that are "heads" or "tails."

California Driving Under the Influence (DUI), or Driving While Intoxicated (DWI) arrests typically result in two different charges. The first is the "Per Se" charge, (California V.C. Section 23152 - Driving Under Influence of Alcohol or Drugs), where the sole concern is whether or not the accused was above the legal limit at the time of driving. The legal limit for driving is now .08 percent blood alcohol content (BAC) in all 50 states.

The second charge is driving under the influence, which focuses on whether or not the driver is impaired. This charge hinges on circumstantial evidence of physical and mental impairment as the result of consuming alcohol or other drugs. California police often use field sobriety tests to gather evidence that supports the theory that a suspected DUI driver was mentally and physically impaired. Although field sobriety tests are optional, most police officers don't share that information with drivers.

Physical and mental impairment is the crux of every DUI prosecution. Experts agree on certain points relating to impairment as the result of consuming alcohol. For example, when it comes to impairment from alcohol, mental impairment always takes place before physical impairment.

Experts agree that it is possible to mask physical impairment that stems from alcohol use through the phenomenon known as "tolerance". However, it is impossible to mask symptoms of mental impairment. Therefore, if a driver exhibits physical impairment, but no mental impairment, that impairment must come from a source other than alcohol. This information is extremely useful to an experienced California DUI defense lawyer.

Physical impairment can stem from a variety of sources. Injuries or other physical disabilities can impair a person's ability to perform on field sobriety tests. Fatigue can impact a driver's performance, as can nervousness. Being forced out of a car by armed police officers under the threat of arrest can provoke the kind of nervousness that will negatively impact performance on field sobriety tests.

No matter how the driver charged with a DUI feels he or she performed on a field sobriety test, our experienced DUI attorneys are prepared to help. The Law Offices of Robert Tayac, located in San Francisco Bay Area, an experienced law firm of DUI lawyers specializing in DUI defense exclusively. We invite you to contact our office for a free consultation about your California DUI case and DMV driver's license suspension hearing.