The first thing that drivers should know about field sobriety tests, including the physical tests and the handheld PAS (preliminary alcohol screening) test, is that they are voluntary for drivers who are 21 years of age or older.  The officer will ask you to take them, but you are free to refuse.  You can politely decline, saying that you have heard the tests are not accurate.  (The law does not, however, allow a DUI suspect to refuse a chemical test at the station or hospital after the driver has been arrested.) 

The Physical Tests

When an officer stops a motorist suspected of driving under the influence, if the officer asks the motorist to exit the vehicle (which the motorist is required to do, if asked), the officer will typically then ask the suspect to engage in one or more physical tests that supposedly determine whether the suspect is drunk to the point of being impaired in driving ability.  These field sobriety tests involve coordination, balance, eye movement and/or language/memory skills.  Generally, you should decline to take these roadside tests.  They will just generate evidence that will be used against you.

Most of the physical roadside tests are of little value in determining impairment.  The National Highway Traffic Safety Administration (NHTSA) has approved only three of the many tests used.  The three tests determined to have scientific validity are: the Horizontal Gaze Nystagmus test, the Walk and Turn, and the One Leg Stand.  Yet, many California law enforcement officers continue to use other tests known to produce meaningless results. Even the tests approved by the NHTSA are far from reliable:

• Horizontal Gaze Nystagmus Test.  Nystagmus is an involuntary jerking of the eyes, a condition influenced by intoxication.  In the horizontal gaze nystagmus (HGN) test, the officer holds a "stimulus" (usually a finger or pen) in front of the suspect's eyes and asks the suspect to follow it with the eyes as it is moved from side to side.  If lack of smooth pursuit or nystagmus is observed while the suspect's eyes track the stimulus, this is a "clue" suggesting intoxication.  The HGN test provides a total of 6 clues that may be observed in administering the test.  If 4 of these 6 clues are observed, the results indicate impairment.  The HGN test is considered the most useful of the three tests approved by NHTSA.
• Walk and Turn Test.  The officer asks the suspect to walk nine heel-to-toe steps in a straight line, turn around, and walk nine heel-to-toe steps back. Clues of intoxication include failure to follow directions, stumbling, stepping off the line, using the arms for balance, an improper turn, or taking the wrong number of steps.  The test provides a total of 8 clues.  If 2 or more clues are present, that suggests impairment.  One problem with the administration of the test is that, in traffic stops, there is often no actual line available, requiring use of an "imaginary" line.
• One Leg Stand Test. The officer requires the subject to stand on one leg with arms down at the side, and to raise and hold the other leg with the foot six inches off the ground while the suspect counts to 30.  Clues of intoxication include: swaying, using the arms for balance, hopping, and problems with counting.  Two of the available 4 clues will indicate impairment.  Needless to say, this test is difficult for persons who are completely sober, particularly if the person has any joint or limb problems, or any disorder that would affect balance.

The NHTSA warns that to be effective, these three approved tests must be given according to exact specifications.  Unfortunately, traffic officers administer these and all other field sobriety tests alongside random highways, on a variety of surfaces, under varying lighting conditions, with traffic whizzing by, to suspects of all ages and physical conditions.  Also, many officers fail to follow the strict protocols required to render the results meaningful, according to NHTSA.  Under real-world conditions, the tests can be difficult for anyone to "pass" – regardless of whether they have been drinking.  This is particularly the case when the person is nervous (who wouldn't be?) or suffers from physical problems or disabilities.  Not only are the tests administered under less than controlled conditions, it is the police officer's subjective opinion which alone determines whether the suspect has "passed" or "failed."  Why take the chance of creating evidence against yourself, when you can simply refuse the tests?

If you did take field sobriety tests, the officer will no doubt want to testify that the results indicate you were under the influence of alcohol or drugs.  Fortunately, we can often show the DMV and Court that the tests were either not tests approved by NHTSA as having scientific validity in determining intoxication, or, that they were not administered properly, rendering the results invalid.  If necessary and possible, our attorneys will also provide other explanations for the observed performance.  

The Roadside PAS Test

Sometimes the law enforcement officer will ask the stopped motorist to take a "Preliminary Alcohol Screening" or PAS test.  This test is administered roadside using a handheld breathalyzer device, and will supposedly reveal the taker's blood alcohol content (BAC).  As with all roadside tests, a DUI suspect who is 21 years of age or older can refuse to take this test.  The results of the PAS test can be highly inaccurate.  It is not the same breathalyzer test given at the station, which uses a larger, more reliable machine.  As with the other roadside tests, if you are over 21, it is voluntary.  Unless you are confident you nowhere near intoxicated, you should politely refuse to take the PAS test.  Again, you can simply say that you have been told drivers should always refuse the PAS because it is unreliable.