Motorists suspected of DUI / DWI are routinely asked by police officers to perform one or more field sobriety exercises. These ”voluntary tests” were developed by police agencies to assist law enforcement officers in making roadside determinations as to whether a motorist is under the influence of alcohol or drugs. Through the performance of these tests or evaluations, the officer subjectively determines how the motorist reacts to and performs the requested tasks. Many knowledgeable DUI / DWI attorneys will advise you not to take any of the field sobriety tests because studies have concluded that the Standardized Field Sobriety tests are “designed to fail”.
A motorist's alleged poor performance on field evaluations may provide the 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, if he or she is going to defend you.
Counsel for the defense 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. These tests, known as the “standardized field sobriety tests” SFST’s, were designed pursuant to numerous federal grants and ultimately sanctioned by NHTSA (the National Highway Traffic and Safety Administration). 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, 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 over the legal limit. The “studies” determined that only the three named evaluations had any reliable correlation (better than 50-50) 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 over the legal limit.
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 many of the officers administering these evaluations do them wrong. Some officers conduct the SFST’s in a manner not approved by the SFST manual. Others grade the evaluations improperly. When done incorrectly, these evaluations have ZERO predicted reliability. Recent research and scientific review of the testing protocols and scoring methodology have brought the NHTSA Standardized Field Sobriety Tests 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).)
A great rift exists among scientific experts on the question of whether field sobriety tests are ``scientific.'' The reason that most credible scientists across America (and in other countries) are unwilling to categorize field tests -- even NHTSA's tests -- as being “scientific” is that too many variables are involved in roadside testing to ever eliminate pure chance and non-controlled circumstances from the equation (e.g., environmental conditions such as lighting and roadway slope). Numerous states, including Texas, Alabama and Mississippi, do not permit HGN evidence to be admitted at trial. The rationale is that this test does not pass well-established rules of evidence for scientifically acceptable tests.
Even NHTSA admits that under optimal conditions (i.e., in an air-conditioned, well lighted room) 35% of sober, drug-free subjects get inaccurate results on the one leg stand test, 32% of sober subjects get flawed results on the walk and turn, and 23% of sober subjects are inaccurately said to be “over the legal limit” on the horizontal gaze nystagmus test.
These are some of the issues that an experienced defense attorney should be prepared to address in preparation for your trial. Thomas C. Mooney is an experienced trial attorney with a tremendous record in successfully challenging the State’s evidence in DUI/DWI cases.