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Field Sobriety Tests

Perhaps the most commonly known procedure in the DUI field is the field sobriety test. Nearly everyone who knows someone arrested for DUI, or all of those who were arrested themselves know about the tests given to a driver suspected of being inebriated following a vehicle stop. Although many are familiar with the use of these tests in the general sense, there are actually very specific procedural and scientific methods which must be employed to ensure the accuracy of the testing and to confirm the officer's initial suspicion of drunk driving.

As the name suggests, field sobriety tests (FST) are performed at the scene of the traffic stop or arrest. The entire purpose of these tests is to confirm the officer's suspicion that sufficient probable cause exists to carry out an arrest for drunk driving. In many instances, by the time the officer gets to the FST portion of the investigation, he has already made a decision in his mind that the suspect is guilty. In these situations, the FSTs just help police obtain additional evidence to use against the defendant.

Tools of Trade – The PAS Device

Practically all law enforcement agencies use a piece of equipment called aPreliminary Alcohol Screening Device (PAS) to help determine whether a driver is under the influence. These devices are designed to be easily transported by officers to roadside investigation scenes, and are utilized to give a initial reading of the blood alcohol content (known as BAC) of the suspect. Although these PAS devices are in essence computers with complex calculating mechanisms, they alone cannot be relied on to make authoritative determinations regarding whether the person is driving with a BAC of .08 or more.

The most widely used PAS device in the state of California is called the Alco-Sensor 4. This particular model has allows the law enforcement official to transfer data obtained through its use. Newer variations of the model also allow the officer to immediately print out data at the scene following the completion of the test. Regardless of the model of PAS device, it is common that all readings obtained during the test are purged from the machine to ensure it remains accurate in future testing.

As previously noted, the device itself may not be relied on to “make the case” for the investigating officer. This subject has been addressed in related California case law in Kodani v. Snyder, 75 CA4th 471 (1999). This case made it official that officers may only use the PAS device as one of several tests used in the field sobriety testing process to determine if an arrest is valid.

There are several procedural steps which must be completed during the use of a PAS device, such as the Alco-Sensor IV. Prior to using the device, law enforcement must advise the suspect that they are seeking his or her permission to administer a PAS test. The officers must also inform the person that they can refuse to submit to PAS testing. However, due to the concept of “implied consent” (that those who choose to drive on California roads are expected to obey the law and thus implicitly consent to test for driving under the influence) a suspect's refusal to submit to PAS testing does not mean that they will get away with not testing at all. A suspected drunk driver is still required by law to submit to a urine test or blood test to determine if they were in fact driving under the influence. However, mere refusal (assuming the officer gave the proper warnings) to take the PAS will not reflect on the defendant's guilt per People v. Jackson, 189 CA4th 1461 (2010).

PAS machines used by any given law enforcement agency undergo calibration and maintenance by those agencies. Since the party responsible for both ensuring the accuracy of the investigative tools and for carrying out the investigation are one in the same, defense attorneys and defendants alike are often suspicious of the reliability of law enforcement methods. To challenge suspicious PAS readings, defense counsel can fight the admissibility of the PAS evidence. This is commonly done through a motion brought under California Evidence Code section 402, called a “motion in limine.” A motion in limine is one made before the start of the trial that requests that the judge not allow certain evidence to be presented at trial.

Once the admissibility of PAS readings is challenged by the defense, the prosecution must seek to establish the reliability of the readings through one of a couple methods. First, the prosecution can show that the testing complied with case law standards related by People v Adams, 59 CA3d 559 (1976). This case set out three requirements which must be independently established to create a proper foundation. Specifically, the prosecution must put forth evidence proving that the operator (police officer) of the device was both qualified and competent to use the device, the test itself was carried out properly, and that the device was functioning appropriately.

Even where the prosecution is able to meet the above listed requirements from People v. Adams, it must still show that other procedures were done correctly, such as that discussed above requiring the officer to give the suspect certain warnings before testing. It can be problematic for the prosecution if it is shown that the officer failed to properly inform the defendant prior to initiating the PAS test.

Other Field Sobriety Tests

Additional methods used in field sobriety testing to not involve the use of a machine or other electronic device. Rather, they are a series of physical and mental tests which examine the suspect's ability to act and think in a “normal” manner where intoxication is already suspected. These types of tests are used in conjunction with the PAS device to make an “on the spot” determination whether the driver has been operating the vehicle under the influence.

FSTs Testing Balance

The Rohmberg Test

This test is often referred to as the “modified position of attention” test. In this test, the suspect is required to stand up straight, close his or her eyes, and then move their head backwards almost as if they where sleeping on their back in a bed. If the suspect's body begins to move back and forth, or sway during this process, police will consider it evidence of being under the influence.

Walk & Turn Test

This test is often portrayed on television shows like “Cops” and is probably the most recognized field sobriety test. In this test, the officer will have the suspect walk an imaginary line in the road for a certain number of steps. Commonly, officers will instruct the suspect to walk in a “heel to toe” manner and then to make an abrupt turn once completing the required number of steps.

The Leg Raise Test

In this test, the suspect is required to stand straight and then lift one of his or her legs for a designated amount of seconds. For example, officers may instruct the suspect to lift his right leg, one foot off the ground, for twenty seconds. Sometimes the suspect may be required to repeat the test using the other leg.

FSTs Testing Coordination
The Finger to Nose Test

In this test, the suspect is required to stand straight with their eyes closed while they attempt to touch their nose with their index finger. In some cases, they may be required to move their head back (similar to the Rohmberg Test) while performing the maneuver. The suspect may have to perform this several times and will often be required to switch hands.

Finger and Thumb Touching Test

With this test, the driver is required to use his or her thumb to touch the tips of all the other fingers on their hand. The officer will try to determine if the touching is accurate and if it is completed in a reasonable amount of time.

FSTs for Mental Capabilities
Alphabet Writing

Officers can instruct the driver to write out the alphabet on a piece of paper provided. With this test, officers are looking at the suspect's ability to write out the alphabet correctly, the time it takes to accomplish this task, and whether the handwriting itself is legible or appears to be abnormal. Usually, the person is also asked to sign their name on the paper.

Counting in Reverse

As the name clearly suggests, this test requires the subject to count i.e. one to ten, and then to reverse count back to the starting number. Officers may modify the test by giving the subject a random number and requesting that they count down from there.

Saying the Alphabet

This test is self-explanatory. A person will be required to say the alphabet in rapid succession. Officers will listen for letters out of order, or skipped ones to determine if the person exhibits signs of intoxication.

Fairness Isn't a Factor!

Often, the tests focused on mental ability will be combined with coordination or balancing tests to make it more challenging to pass. Officers are trained to believe that anyone could easily complete these supposed simple tasks while sober. However, this is not always the case. The tests fail to take into account the unique mental and physical capacities which differ from one person to another. Furthermore, the instructions for the tests given by officers are not always clear or definitive enough to determine what constitutes  passing or failing. Since law enforcement has significant leeway in conducting these tests and determining the results, it is important to have a dui attorney who is thoroughly familiar with the process to help you fight every aspect of your case.

FST Eye Exams
Pupil Reaction

In this test, officers will shine a flashlight into the eyes of the driver in an attempt to measure the  of pupil dilation. The theory behind this is that in normal eyes, a pupil should adjust rapidly. However, when someone is intoxicated, it can take longer for the pupil to dilate. Officers will use a slow dilation as evidence that someone is in fact driving under the influence.

Nystagmus Test

This test checks for a twitching movement in the eyes when they are prompted to look at an object at a certain angle. The officer uses an small object and holds it in front of the suspect's face. The officer then moves it back and forth and asks the subject to follow its movement. While this is going on, the officer is looking at the person's eyes to determine at one point they begin to disrupt the fluid movement. It is generally accepted by law enforcement that a person whose eyes begin to twitch before reaching a forty five degree angle is likely intoxicated.

Police Officers Are Not Scientists

When it comes to eye exam FSTs, it goes without saying that police officers do not have the same amount of education, training, or ability as your local optometrist. Although these tests appear to be scientific in nature, they actually fail to employ many scientific principles. Thus, they continue to be challenged by defense counsel because of the potentially prejudicial way they are presented in the prosecution's case as scientific in nature. Studies which have been done by the scientific community support the idea that FSTs amount to a pseudo-science at best. Even the National Highway Traffic Safety Administration (NHTSA) has previously looked into the matter and determined that many of the tests did not produce reliable results.

Aside from reviewing the FST procedures used, NHTSA went step further and issued a recommended testing routine with specific instructions for carrying out testing. The NHTSA has declared that only three of the tests can produce objectively accurate results in police DUI investigations: the nystagmus test, the leg raise test and the walk and turn test. To increase and maintain the scientific integrity of these tests, the NHTSA has issued standard guidelines to instruct officers as how to properly administer these tests. Unfortunately, for California residents, the state has still not adopted the NHTSA standards and officers remain free to conduct unreliable testing procedures and to arrest DUI suspects using little more than their gut instinct on guilt. Thus, it should be duly noted that DUI arrests in California are not always synonymous with justice. However, the factual circumstances of many cases are ripe for an experienced defense attorney to challenge the unfair enforcement techniques.

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The Law Office of Michael Rehm is a DUI and Criminal Defense Law Office that practices throughout San Diego County. Michael Rehm is available for free, confidential consultations at (619) 787-3456.