San Diego DUI Lawyer Explains Field Sobriety Tests

San Diego DUI Lawyer:  Field Sobriety Tests are VOLUNTARY

San Diego DUI LawyerSan Diego DUI Lawyer
The most important part of the discussion of field sobriety tests is that they are voluntary.  While California's implied consent laws punish drivers who refuse a chemical test after being arrested, the field sobriety tests officers use to determine whether they have enough evidence to make an arrest are VOLUNTARY.  If requested to perform any field sobriety test by a law enforcement officer, drivers should politely decline.  Studies have shown a correlation between impairment to drive and the Standardized Field Sobriety Tests (SFSTs) that most law enforcement agencies use to determine impairment.  Still, these tests can produce many false positives, as they are difficult to perform.  Further, officers are trained to use these tests to build evidence of drunk driving, not to actually determine whether a person can safely operate a motor vehicle.  Essentially, it is highly probable that even a sober person could "fail" the tests.  The way to "beat" the field sobriety tests is to decline to perform them in the first place, limiting the amount of evidence the police officer can gather against you. 

The National Highway Traffic Safety Administration (NHTSA) recognizes three field sobriety tests as the Standardized
Field Sobriety Tests (SFSTs):  The Horizontal Gaze Nystagmus Test (HGN), One Leg Stand Test, and Walk and Turn test.  Additionally, the California Highway Patrol, responsible for more DUI arrests than any law enforcement agency in California, also makes the Romberg Balance test part of its standard DUI investigation.  Below, you will find a brief overview of each test as well as some of the possible defenses available despite an officer's conclusion that the driver failed the test.  note:  these tests have been approved for use in alcohol-related DUI arrests, but do not have a proven correlation to drug impairment.

The HGN test is an observation of a subjects eyes and how they move while following an object from side to side.  Nystagmus is a very slight twitching of the eye during pursuit.  In theory, a sober person's eye would track the officer's pen or finger smoothly, rather than in a jerky fashion.  The difference can be likened to a Rolex watch (smooth pursuit of a sober eye) and a Timex (ticking-like movement).  There are many problems with this test, including a failure of the police officer to properly administer the test.  First, officers often perform the test while the subject is seated, in direct ignorance of proper procedure.  Additionally, officers rarely use any scientific tools or methods to determine angles of onset.  If an officer's perception is flawed, they may observe nystagmus where there is none.  Furthermore, there are causes of nystagmus that have nothing to do with alcohol.  Roughly 5% of the population has naturally-occurring nystagmus, while others may have nystagmus caused by the turbulence of an accident (vestibular nystagmus), fatigue or eye strain.  Police are not medical doctors and cannot distinguish nystagmus caused by alcohol impairment.  If you have submitted to an HGN test and were arrested for DUI, you need a knowledgeable, experienced San Diego DUI Lawyer on your side.

The One Leg Stand test, as the name suggests, asks the subject to stand on one leg, while raising the other off the ground 6 inches.  The officers are testing for balance here, as well as the cognitive ability to follow directions, count and more.  Frequently, the officers will write in their reports that the subject put their arms out to the side for balance and use this as evidence of impairment, i.e. of failing the sobriety test.  The problem is that the officers rarely instruct subjects NOT to do this.  It is a natural instinct that would be exhibited by people stretching in a work out class, and others who may find themselves needing to balance on one leg.  Drunk or sober, this is an unnatural position and not one we practice.  As with the HGN test, being involved in a traffic collision (the root cause of many DUI investigations), can affect results.  Further, medical conditions, injuries, foot pain, back pain, choice of footwear, weather conditions, conditions of the testing surface and more can affect the reliability of these tests.  It takes an experienced DUI lawyer, who understands how the FSTs are properly administered to bring out the officer's failures on cross-examination.  In many cases, your San Diego DUI lawyer can get video footage of your driving pattern and/or field sobriety tests.  While videos will rarely be of sufficient quality to challenge the officer's HGN observations, a close viewing of the video may reveal errors the officer made with the one leg stand, walk and turn, and Romberg tests.

This is a test that officers will typically demonstrate only partially, and, like the one leg stand test, officers will have a subject perform the test under less than ideal conditions.  Though actual lines are available, the officers usually have the subject walk 9 steps ("there and back") on an imaginary line, then write in the report that the subject stepped off of the imaginary line.  The turn itself, and the first two to three steps following the turn are where most people tend to have trouble.  As with the one-leg stand test, sports injuries, arthritis, back pain, foot problems, bad knees, bad ankles, uneven roads and more can make the test quite difficult.  Additionally, fatigue can be an issue.

The traditional Romberg test asks the subject to stand, feet together, eyes closed and count.  Here, the officer would be looking for swaying, even toppling.  Minor swaying is normal, and not indicative of impairment.  The way that CHP and other law enforcement agencies employ this test is often called a "modified Romberg test" because subjects are not only asked to close their eyes, but also to tilt their head back.  Like the one leg stand and walk and turn tests, this places subjects in an unfamiliar, unnatural and uncomfortable position.  Fatigue, injuries, medical conditions, footwear and more can affect performance on this test as well.

The first "breathalyzer" machine that you encounter/encountered during a DUI investigation is called a Preliminary Alcohol Screening test ("PAS").  The PAS utilizes a fuel cell technology that is not as accurate as the testing devices used at the station.  Accordingly, its results are generally not sufficient to prove BAC, but are relevant to the officer's decision to make a DUI arrest.  As such, the PAS is not a chemical test, but rather a sobriety test used in the field to help an officer determine impairment.  The legal significance of this designation is that the test, like all FSTs, is VOLUNTARY.  That's right, you can (and probably should) decline to take this test and will not have any adverse consequences.  In fact, without a PAS result, it is more likely that your attorney will be able to challenge the arrest in court or at your DMV hearing.  If you did happen to submit to a PAS test, your lawyer may be able to use the result to your advantage, particularly if that result is lower than any later-performed test.  This can help with the Rising BAC defense, perhaps the most important defense in most alcohol-related DUI cases.

Rising BAC, Mouth Alcohol, Medical Conditions, Chemical Test Accuracy, Driving Pattern, Did Police Follow Proper Procedure?, and Challenging a Bad Traffic Stop.


If you have been arrested for DUI, one of the possible defenses will be to counter the officer's conclusions regarding your performance on field sobriety tests.  This can help to establish that you were not impaired and/or that the arrest was unlawful, potentially saving you from a criminal conviction and driver's license suspension.  Whether you are facing a first time DUI, DUI with a prior, DUI causing injury or felony DUI, the consequences can be severe and you should do your best to avoid a conviction and save your license.  Contact the Law Offices of Nicholas Loncar for a Free Consultation with a San Diego DUI Lawyer.

Nicholas M. Loncar, Esq.
San Diego Criminal Defense Attorney
San Diego Expungements Lawyer
By Nicholas Loncar      


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