Field Sobriety Tests

For persons accused of DUI in California, Field Sobriety Tests are generally used to determine if a person has been driving while intoxicated, and to support whether or not there is probable cause to arrest the driver for DUI. (That includes reasonable cause for your DMV hearing).

Most drivers are not aware that there are only three recognized and standardized field sobriety tests. The Standardized Field Sobriety Tests (SFST)s are a battery of three Field Sobriety Tests administered and evaluated in a standardized manner to obtain validated indicators of impairment and establish probable cause for arrest. These tests were developed as a result of research sponsored by the National Highway Traffic Safety Administration (NHTSA) and conducted by the Southern California Research Institute. A formal program of training was developed and is available through NHTSA to help police officers become more skillful at detecting DUI suspects, describing the behavior of these suspects, and presenting effective testimony in court.

Formal administration and accreditation of the program are provided through the International Association of Chiefs of Police (IACP). Unfortunately, many officers either did not attend the formal training or relax the strict standards of the three tests, sometimes adding tests that are not recognized. The three Field Sobriety Tests of the SFST battery group of impairment tests are:

These Field Sobriety Tests are administered systematically and are evaluated according to measured responses of the suspect.

HGN Testing

Horizontal gaze nystagmus (HGN) is an involuntary jerking of the eyeball which occurs naturally as the eyes gaze to the side. Under normal circumstances, nystagmus occurs when the eyes are rotated at high peripheral angles. However, when a person is impaired by alcohol, nystagmus is exaggerated and may occur at lesser angles. As our Orange County DUI Attorney knows, an alcohol-impaired person will also often have difficulty smoothly tracking a moving object. In the HGN test, the officer observes the eyes of a suspect as the suspect follows a slowly moving object such as a pen or small flashlight, horizontally with his eyes. The examiner looks for three indicators of impairment in each eye: if the eye cannot follow a moving object smoothly, if jerking is distinct when the eye is at maximum deviation, and if the angle of onset of jerking is within 45 degrees of center. If, between the two eyes, four or more clues appear, the suspect likely has a BAC of 0.10 or greater. NHTSA research indicates that this test allows proper classification of approximately 77 percent of suspects.

The police officer looks for three indicators of impairment in each eye:

The eye cannot follow a moving object smoothly;
Jerking is distinct when the eye is at maximum deviation, and
The angle of onset of jerking is within 45 degrees of center.

If, between the testing done on both eyes, four or more clues appear, the suspect likely has a BAC of 0.10 or greater. NHTSA research indicates that this test allows proper classification of approximately 77 percent of suspects. However, there are known defenses to HGN for this test in DUI cases.

HGN may also indicate DUI Drugs (DUID), in that it may indicate consumption of seizure medications, phencyclidine, a variety of inhalants, barbiturates, and other depressants.

Divided Attention Testing

The walk-and-turn test and one-leg stand test are “divided attention” tests that are supposed to be easily performed by most sober people. They require a suspect to listen to and follow instructions while performing simple physical movements. Impaired persons have difficulty with tasks requiring their attention to be divided between simple mental and physical exercises.

The Walk and Turn test

In the walk-and-turn test, the subject is directed to take nine steps, heel-to-toe, along a straight line. After taking the steps, the suspect must turn on one foot and return in the same manner in the opposite direction.The examiner looks for seven indicators of impairment: if the suspect cannot keep balance while listening to the instructions, begins before the instructions are finished, stops while walking to regain balance, does not touch heel-to-toe, uses arms to balance, loses balance while turning, or takes an incorrect number of steps. NHTSA research indicates that 68 percent of individuals who exhibit two or more indicators in the performance of the test will have a BAC of 0.10 or greater.

The One Leg Stand Test.

In the one-leg stand test, the suspect is instructed to stand with one foot approximately six inches off the ground and count aloud by thousands (One thousand-one, one thousand-two, etc.) until told to put the foot down.

The officer will time the subject for 30 seconds. The officer looks for four indicators of impairment, including swaying while balancing, using arms to balance, hopping to maintain balance, and putting the foot down. Our Orange County DUI Lawyer learned that NHTSA research indicates that 65 percent of individuals who exhibit two or more such indicators in the performance of the test will have a BAC at 0.10 or greater.

The effectiveness of SFST test in court testimony and evidence depends upon the cumulative total of impairment indicators provided by the three-test battery. The greater the number of indicators, the more convincing the testimony. Because SFST is administered according to national standards and is supported by significant research, it has greater credibility than mere subjective testimony.

Testing Accuracy

The NHTSA manuals (plural here, because 6 separate versions have now been released) say that if the FST tests are not performed properly, or if conducted without adhering to the training protocols, such actions “compromise” the validity of these evaluations.

The HGN evaluation, when performed correctly on proper subjects, had a 77% “claimed” reliability rating. The Walk-and-Turn exercise, when conducted properly on a qualified subject on a dry, level surface, was found to be 68% reliable. The One-Leg-Stand exercise, when conducted properly, on a qualified subject on a level, dry surface and under proper instructions and were correctly demonstrated and scored, reportedly yields about 65% reliability. Our DUI Attorney in Orange County, who is certified in field sobriety instruction, can tell you that, if all are done correctly, up to 83% correlation to a BAC of 0.10% or more may be expected.

Knowledgeable Orange County DUI defense attorneys 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.

Also, our Orange County DUI attorneys have learned that recent research and scientific review of the testing protocols and scoring methodology have brought the NHTSA “Standardized Field Sobriety Tests (“SFSTs”) into serious question. 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)).

Alternative Testing Methods:

Sometimes, an officer will encounter a disabled driver who cannot perform the SFST. In such cases, some other battery of tests such as counting aloud, reciting the alphabet, or finger dexterity tests may be administered. Several appellate court decisions have indicated that, if you administer a test that requires the subject to respond orally in other than a routine information-giving fashion, such as requiring them to indicate the date of their sixth birthday, and if they are in custody at the time, the police in a DUI must read your Miranda rights first, because you are seeking information from them that is testimonial or communicative in nature.

Tests given by some officers may include reciting the alphabet (or a portion thereof), picking up coins off the ground, patting or hand clapping, estimating time, counting backwards, reciting the alphabet, touching fingers to the thumb in a pattern set by the officer, or touching index fingers to the tip of the nose while the person’s eyes were closed and head tilted back. Some have in the past involved strange, one-legged tapping on the roadway with a raised foot. These “made-up” tests were administered to subjects without any scientific or empirical basis for reliability in detecting an impaired driver. These tests were designed for failure, not for fairness. Even worse, police officers often forced people to perform these voluntary evaluations, thereby violating these citizens’ rights.

Some “non-standardized” tests are so ridiculous and difficult that proof of non-validity was easy with almost any jury or judge. Today, officers who lack NHTSA training invariably cannot cite any studies or scientific research which “validated” their tests, the scoring (e.g., “pass” or “fail”) or their testing methods. Almost always, no scoring system is used on tests which do not adhere to NHTSA guidelines. If non-standardized tests are used, the number of errors that are required for a subject to fail is totally subjective with each officer. Hence, the untrained officer is usually an easy target for a skilled and knowledgeable criminal defense attorney who knows the “limitations” of these field tests.

The Voluntary Nature of FST Tests:

Recognize that these tests are completely voluntary. These voluntary “tests” (yes, voluntary) are developed NHTSA and implemented 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.

Almost EVERY knowledgeable top Orange County DUI attorney will say to you, “NO. Don’t attempt ANY ‘field tests’ — EVER.” That is because many studies have concluded that the Field Sobriety Tests are “designed to fail” even sober drivers.

Your 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, if he or she is going to defend you.

Orange County DUI defense attorneys usually 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. An attorney representing you must attack the factual and legal issues that may arise regarding the officer’s scoring and evaluation of the field tests.

The reason that most credible scientists across America (and in other countries) are unwilling to categorize Field Sobriety 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).

Even NHTSA admits that Field Sobriety Tests 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. By comparison, polygraph (lie detector) tests are more than 90% accurate when conducted by a qualified operator), and (absent a stipulation by both parties) are still not permitted into evidence by most courts.

Preliminary Alcohol Screening (PAS) Tests:

A portable breath testing device may be used by police officers in determining whether or not a motorist is under the influence of alcohol. California had previously banned the use of these voluntary “non-evidential” screening devices for use at trial but allows it at a pre-trial hearing at which “probable cause” for arrest is involved, or to be used to show the presence of alcohol.

Like other Field Sobriety Tests, these devices are used at the roadway. Often, police officers do not regularly check the devices for calibration. Furthermore, the manufacturer’s instructions (e.g., failing to observe a 15 minute deprivation period, waiting at least 4 minutes between tests, or clearing the prior test results) for proper use are routinely ignored. California’s Administrative Code, Title 17, contains all the information necessary for what constitutes a valid blood or breath test.

Some police agencies try to use these roadside testers as evidential tests. This is accomplished when a small printer is attached to the breath test apparatus. Unless your jurisdiction uses such a device as an official state-mandated breath test, no person should ever submit to these devices and risk a false positive result and almost certain arrest. Politely decline to give this voluntary sample, although be aware that refusal of an official breath or blood test later can be considered a refusal, triggering a license revocation.

If you have any other questions, contact our firm or call us at (877) 568-2977, to make sure you speak with, visit, or email a DUI lawyer Orange County today.