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Field Sobriety Tests

Field Sobriety Tests

Drivers suspected of DUI / DWI are routinely asked by police officers to perform one or more field sobriety tests. These voluntary "tests" (yes, voluntary) were developed by police agencies to assist law enforcement officers in making roadside determinations as to whether a driver is under the influence of alcohol or drugs. Through the performance of these tests or evaluations, the police officer subjectively determines how the motorist reacts to and performs the requested tasks.

Almost EVERY knowledgeable DUI / DWI attorney will say to you, "NO. Don't attempt ANY 'field tests'---EVER." That is because many studies have concluded that the SFSTs are "designed to fail".

A driver's alleged poor performance on field evaluations may provide the "probable cause" (legal justification) an officer needs to arrest a person for impaired driving and may also become part of the proof used to later convict the person at trial. Therefore, it is very important that, in defending you, your defense attorney know as much or more about these tests as the police.

One sure way to know that your DUI lawyer is up to date: is your lawyer "NHTSA certified"? Certified as a "student"? Or certified as an "instructor". Ask him/her. This training has been available to defense attorneys since 1994.

Defense lawyers should challenge the subjective nature of the evaluations, the accuracy of the principles behind the tests, the accuracy of the administration of the tests, the credibility of the officer who "requested" the tests, and challenge all circumstances connected with the evaluations. The attorney representing you must attack the factual and legal issues that may arise regarding the officer's scoring and evaluation of the field tests.

Only three tests have been "scientifically" studied (in lengthy studies paid for by the federal government) and represented to have any measure of reliability in helping an officer predict whether a subject is above a certain legal limit (0.10 BAC, in the original testing).  These tests, known as the "standardized field sobriety tests" [SFSTs], were designed pursuant to numerous federal grants and ultimately sanctioned by NHTSA (the National Highway Traffic and Safety Administration) beginning in 1984.  These three tests are (1) the walk and turn [WAT] test, (2) the one leg stand [OLS] test, and (3) the horizontal gaze nystagmus [HGN] test.  However, the manuals (plural here, because 6separate versions have now been released) say that if not performed properly, or if conducted without adhering to the training protocols, such actions "compromise" the validity of these evaluations.

Starting in the 1970's, NHTSA began studying and funding "field tests" to see if any of the dozens of police exercises had any correlation to showing if a drinking driver had a blood alcohol level of 0.10 grams percent or higher.  The "studies" determined that only the three named evaluations had any reliable correlation better than 50-50 (flipping a coin and guessing 'heads', being a 50-50 reliability test, for example) to identify a person having a BAC of 0.10% or more.  These evaluations in no way were used to determine whether a driver is impaired . . . only whether the person may be 0.10 or more.

The HGN evaluation, when performed correctly on proper subjects, had a 77% "claimed" reliability rating.  The WAT exercise, when conducted properly on a qualified subject on a dry, level surface, was found to be 68% reliable.  The OLS exercise, when conducted properly, on a qualified subject on a level, dry surface and under proper instructions and where correctly demonstrated and scored, reportedly yields about 65% reliability.  Cumulatively, if all are done correctly, up to 83% correlation to a BAC of 0.10% or more may be expected.

Knowledgeable criminal defense lawyers know that 98% or more of the officers administering these evaluations do them wrong, or conduct them in a manner (or on a test subject) not approved by the SFST manual, or grade the evaluations improperly, as per the manual, or ALL OF THE ABOVE.  When done incorrectly, these evaluations have ZERO predicted reliability.  Hence, a top-notch DUI/DWI lawyer can cross-examine the arresting officer using his/her OWN training materials that the federal government and YOUR state government have approved.

Recent research and scientific review of the testing protocols and scoring methodology have brought the NHTSA "Standardized Field Sobriety Tests ("SFSTs") into serious question.  Courts across America are taking a closer look at the original research, to see if proper scientific methods were employed in the initial research.  More and more courts are now saying "no" to these questions.  In a recent New Mexico case, a high-level court has declared that the person who "developed" the tests (Dr. Marcelline Burns) was not qualified to testify as an expert witness about the scientific principles behind the HGN test.  (Lasworth v. State, 42 P.2d 844 (N.M. App. 2001).)

Attorney Kathleen Carey

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Kathleen Carey is an experienced and passionate advocate for her clients.

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