Experienced Utah DUI Attorney Explains Intoxilyzer And Field Sobriety Tests

Understanding the machines used for DUI testing

Field sobriety tests use devices that estimate your blood alcohol content (BAC) from a sample of your breath. Some of the more common brand names for such devices include Breathalyzer, Intoxilyzer, Alcosensor, Alcotest and Breathkey. All of these devices serve the same purpose and provide primary evidence in many DUI arrests. If you are going to mount a solid defense against a DUI arrest, you must understand these tests, how they work and their common faults. An experienced DUI law firm, such as the Law Offices of Carl N. Anderson, III, PLLC in Salt Lake City, can provide these explanations. Carl N. Anderson, III is actually qualified to administer the Standardized Field Sobriety Tests (SFST) and teach and evaluate law enforcement on proper SFST administration.

What’s A Field Sobriety Test?

Field sobriety tests are a set of physical exercises that police use to justify arrest. People who are stone cold sober fail these tests every day. They include:

  • Standing on one leg without falling over
  • The walk-and-turn test, to see if you can move in a straight line
  • Touching finger to nose
  • The horizontal gaze test, sometimes using a penlight
  • The ability to count on your fingers
  • Finger tracing coordination

How You Can Beat the Standardized Field Sobriety Tests

A poor performance in a field sobriety test may be the result of any number of factors not related to consuming alcohol or drugs. Environmental conditions such as poor lighting, an uneven surface and weather may affect your performance. Your own physical condition such as fatigue, nervousness, depression, or prescription medication may also affect your ability to perform some parts of the test, but not necessarily your ability to drive safely.

The Reality Behind Field Sobriety Tests

The first field sobriety test was invented in 1954 by an Indiana State Police Captain named Robert Borkenstein, who eventually became a doctor and a professor at Indiana University at Bloomington. This invention allowed law enforcement a non-invasive way to immediately determine the BAC of a DUI suspect.

One thing the field sobriety tests have never been able to determine, though, is the level of intoxication of a subject. Due to gender, weight, race and other factors, different people react in different ways to the same BAC test, and the results often vary between individuals who consume the same amounts of alcohol.

Today, BAC tests estimate the BAC of subjects indirectly by measuring the amount of alcohol in their breath through one of two technologies:

  • Infrared spectrophotometer technology
  • Electrochemical fuel cell analysis — a less accurate method often used in the field as a sort of preliminary breath test

Common Problems with BAC Tests

Field sobriety tests are subject to numerous failures and errors, all of which can form the basis of a legal DUI defense or the pursuit of reduced charges for DUI. These errors include:

  • Temperature, which affects field sobriety test results tremendously, both in terms of atmospheric temperature and the body temperature of the subject
  • Some tests assume a certain baseline volume of alcohol in the bloodstream when in reality this presumed constant varies wildly in adults
  • Breathing patterns impact the accuracy of a breathalyzer test
  • Law enforcement officers frequently misuse field sobriety devices or fail to maintain or calibrate these devices correctly
  • Breathalyzer tests do not account for drug or narcotic-based DUIs

More Articles To Help You Understand Field Sobriety Tests

  • Can I Refuse a Breathalyzer Test?
  • The Nystagmus Test
  • Salt Lake City Implied Consent Laws
  • Constitutional Rights
  • DUI Checkpoints

Unparalleled experienced fighting DUI charges and understanding field sobriety tests

Utah attorney Carl N. Anderson, III started out as a Nebraska County attorney, where he gained considerable experience litigating cases involving DUIs, field sobriety tests and other elements of traffic stops. Let him put that experience to work for you. Contact the Law Offices of Carl N. Anderson, III, PLLC online or at (801) 997-9534. He is licensed to practice law in Utah, Colorado and Nebraska.


Get your questions answered – Call for a consultation (801) 997-9534