Sobriety Can Be Subjective

Sobriety Can Be Subjective

An experienced Orange County DUI lawyer may tell you that it can be difficult to determine if a driver’s blood alcohol concentration is above the legal limit and deserving of a DUI sentence, even after a field sobriety test. You may be wondering: what is the difference between a blood alcohol concentration test and a field sobriety test, and how can that distinction affect your DUI case?

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What Is a Blood Alcohol Concentration Test?

  • A blood alcohol concentration (BAC) test is a reliable chemical test that measures an individual’s blood alcohol concentration, or the percentage of alcohol in a person’s blood.
  • Usually, law enforcement officers administer blood alcohol concentration tests using breathalyzers on motorists suspected of driving under the influence.

How Reliable Are BAC Tests?

  • A margin of error is always involved in any test method, but a BAC test is based on scientific studies and has a small margin of error.
  • BAC tests are the best indicators that law enforcement currently has to accurately determine blood alcohol concentration.

What Is a Field Sobriety Test?

  • A non-chemical test that measures driver impairment based upon police officer observation.

How Reliable Are Field Sobriety Tests?

  • They are often less dependable than blood alcohol concentration tests because they rely upon individual observation, so your Orange County DUI lawyer may attempt to challenge the validity of any field sobriety tests performed upon you.
  • Also, it is often difficult for police officers to interpret the sobriety of someone whose normal behavior is unknown.

If They Are Unreliable, What Are Field Sobriety Tests Useful For?

  • Providing probable cause for a DUI detainment or arrest
  • Establishing driver impairment (either physical or mental)
  • Relating alcohol and impaired driving

Types of Field Sobriety Tests

  • Walking a straight line, such as a traffic lane divider, heel to toe (or simply standing heel to toe)
  • Holding arms out and touching the tip of each index finger to the tip of the nose
  • Counting fingers
  • Counting backwards from a specific number
  • Balancing on one foot, sometimes while simultaneously touching index fingers to nose
  • Reciting or writing the alphabet backwards and/or forwards
  • Tracing a figure with pencil and paper
  • Horizontal gaze nystagmus, or HGN: following a stimulus (usually a police officer’s finger or flashlight) with eyes without moving the head
  • Toe touch


After your field sobriety test and consequent DUI arrest, you may be feeling helpless.  However, an experienced Orange County DUI lawyer may be able to help you turn your life around.  If you have questions about your DUI arrest, call the Law Office of Mike Coffey Attorney at Lawand the Law Office of Mike Coffey Attorney at Lawtoday at (800) 706-7888.